You could as well ask, "why run a lighter oil unless it's necessary?".

I'm going to talk to my dealer, who just got back from seeing Alfa in Italy, as to whether or not anything was mentioned about 10w-60 oil.

Del

Seattle

My mechanic didn't seem to think that it would hurt anything putting the 10w60 oil in my car (it has always had 20w50) at the heavy end and thought that it would probably be a good idea for cold starts during the winter anyway.

Tim Annett
1995 164 Quadrifoglio
Laverdas!

The proof is in all of the V-6's that have never had a bottom-end problem or failure that is related to oil weight (which is the vast majority of them on the road). Just because some cars have had spun rod bearings does not point to oil viscosity as the root cause. If there is data that shows that the vast majority of failed engines was because 'too light of oil was used' it would be a different story; but from what I have read and been told the V6 has a strong bottom end and its pretty rare to for the bearings to go out on one of these cars unless a massive loss of oil pressure has occurred (not simply a condition of low pressure).

>You could as well ask, "why run a lighter oil unless it's
>necessary?".
>

Because lubrication is improved and friction is reduced with a lighter weight oil. Any flowing liquid generates friction due to shear-flow forces, and lower viscosity oils minimize the heat generated by this flow friction. In addition oil moves through the system more quickly flushing contaminants and cooling the engine better than a thicker, slower moving oil. It does not take a whole lot of pressure to keep the journal bearings afloat on the oil film; so it does not make sense to have an overly high system pressure. The viscosity of cold oil is what causes engines to wear faster (due to friction/viscosity) and look at the pressure the gage reads when cold, not way higher than when warm (of course the pressure relief may be opening when cold also). I'll repeat what I said before; use a heavier oil if you have verified a condition of weak oil pressure at operating temp or if you live in a hot climate. If you have oil consumption that you wish to slow down; xx-50 can slow it down. 60wt seems a bit excessive. Thats JMHO.

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A journal (rod) bearing works by having the pumped oil form a wedge between the journal and the bearing surface, not just maintaining a static film. The journal can be considered as a roller climbing the oil wedge or ramp, not touching the bearing surface. If the viscosity of the oil is too light, that wedge will not form correctly because the oil will flow out too quickly. High contact friction can occur in that case leading to eventual failure, journal wear, and bearing seizure. Also, the thickness of that wedge is what enables the bearing to reduce/eliminate the pounding of the rod on the journal as the engine runs. Granted, you could conceivably have too high an oil viscosity, once again creating an insufficient wedge, but we have no evidence that hot 60w is too much.

Stating that friction is reduced with a lighter viscosity oil is ignoring how a journal bearing functions. Unstated is the requirement that the hot oil maintain sufficient film strength to protect the sliding contact bearing surfaces in the rest of the engine. A lighter oil will not provide as much of that needed protection. Race engines are often run with light viscosity oils because there is a realized hp gain, but then again these engines are not designed for longevity (F-1 engines are noted for being good for about 1 race, if that!). One of the car rags stated that many sport engines such as the Alfa v-6 used 10-40 in lieu of a perhaps more normal 10w-50 for that very reason.

Determining the correct range of viscosities to be used in an engine is a complicated subject, and many millions have been spent on research by both the engine designers and the oil producers. This v-6 is a low oil pressure running engine, and the viscosity of the hot oil film absolutely must be high enough to form the journal wedge at all oil pressures, rpms, and oil temps without being too high. Go too light and you possibly shorten the life of the engine. Since we are not privy to the engine calculations, we cannot say what would be optimum.

It will be interesting to see if the 10w-60 recommendation by Alfa turns out to be true. Certainly, BMW had to go to 10w-60 for the M engines because of failures.

cheers,

Del

Seattle

I'd be vaguely interested in using 10/60 oil to reduce oil consumption (currently about 400 miles / (UK) pint) and to keep the tappets quiet but I imagine a 10/60 oil would have to be synthetic? I currently use 15/40 ordinary mineral oil because someone once told me that the smaller the gap between the numbers, the less viscosity index improver had to be added to the oil and therefore, the longer it would last. This seems to be true as when I used the same brand of 10/40, I could sometimes (after working it really hard on a hot summer day) just about get the oil light to flicker at idle. I can't do this with the 15/40 (although it has been a lousy summer this year in the UK!).

One final point, even using non-synthetic 10/40 and more recently, 15/40, changed regularly, the engine has done 215,00 miles and will probably outlast the rest of the car! Is there any point, therefore, in using even better oils?

You are correct here; the factors would be RPMs, Oil Temp, Bearing Clearance (Oil Wedge Thickness), Bearing Size. These engines were likely designed to run on 10-30, with 10-40 as recommended for safety margin. Then all of us Alfa enthusiasts bumped the viscosity to 20-50 to slow oil consumption. Now we are at 60wt.

15 psi is what is required for a normal operating engine at idle with no load; this is stated in the service manual. Heavy engine load will require more pressure; but a properly functioning oil pump will provide over 60psi to the bearings and that should be plenty of oil pressure under most driving conditions (we're not talking hotlaps at the track; all bets are off on engine survivability when you drive them that hard). Remember that these are production vehicles not racecars; and even racecars often times have engine failures while running at maximum outputs.

>One final point, even using non-synthetic 10/40 and more recently,
>15/40, changed regularly, the engine has done 215,00 miles and will >probably outlast the rest of the car! Is there any point,
>therefore, in using even better oils?

Exactly. Why all of a sudden a worry about proper oil weight? These cars have logged well over 100k miles without rebuild, now we are supposed to dump racing oil in them? If there were a problem with oil weight it would have been addressed with the GTV6. If it is an engine temp issue; I would sooner do the fixes that Steve and Del have come up with (radiator fan/ fan temp sensor) to correct the bigger problem (overheating and operating too close to temp extremes).

The GTV6/Milano service manual clearly states that the v-6 even then was to use 10w-50 or 15w-50 for most brands of oils, considered by most at that time to be a rather avant garde choice. As mentioned in one of the car magazines previously, however, sport engine hp ratings are often "pumped up" by reducing the viscosity of the oil, to gain several hp for advertising but potentially reducing long engine life. The logical assumption is that the Alfa 164 v-6 viscosity recommendations were reduced to 10w-40 for this very reason. I strongly suspect that's why while you never hear of a GTV6/Milano engine spinning a rod bearing, there are more than a few accounts of 164 engines suffering this very problem. My feeling is that the switch from 10w-50 to 10w-40 for the 164 is a causal factor, since the original design called for the 50 weight.

I prefer to stick to Alfa's original recommendations and use a modern xxw-50 oil (regular or synth, whatever), and if Alfa ends up recommending the use of 10w-60 for the v-6, I'll consider it. Yes, I think that the engine if taken care of will last longer than I will probably have the car, but if the cost of the newer oils is not prohibitive, then why not optimize the situation for the future.

Del

Seattle

Wooooaaahhh!

I hope not!!!!

My oil light doesn't come on until about 5 psi and it usually ticks over with about 0.5 bar on the gauge when warm. As that's only about 7-and-a-bit psi I guess I've been living on borrowed time since I've had the car!

(surely it can't be 15 at idle????) can it???

Required oil pressure is a function of flow requirements. Low or high pressure is not the issue, quantity and rate of flow are the key issues. The oil pump has to generate enough oil pressure to deliver sufficient oil through the bearing surfaces to keep the oil cool enough so that it doesn't break down. That wedge requires oil with certain viscosity characteristics to maintain the film. Excessive heat eventually causes components of the oil to flash off and if severe enough the film breaks down and bearing failure ensues very quickly. If it weren't for the heat the bearings could have a sealed oil or grease supply as many slow speed cool running bearings do. The flow of oil in an engine is essential to keep the oil in the bearing cool enough to maintain that wedge.

So, heavier visocity oil is really oil that resists film breakdown better than lower viscosity oil. But, the number is only one factor. Synthetic oils are much more resistant to film breakdown than conventional oils, generally because they have less volatile components and more of the long chains that preserve oil film. This is why lower viscosity synthetic oils give equal or better protection than heavier conventional oils.

That 60 number is the hot number and is not a measure of actual viscosity but a performance number. For multi grade oils the numbers refer to the fact that the hot performance of the oil is equivalent to a single grade conventional oil with that number. The W or Winter number indicates that the flow characteristics of the oil are equivalent to a single grade conventional oil with that number, at the specified winter temperature. The W number does NOT refer to the ability of that oil to protect the engine, only the higher number does that.

Obviously, no one wants a 0W weight single grade oil in their crankcase, but if it is a multi grade and especially a synthetic multi grade it will have cold weather viscosity similar to a 0W conventional oil but the engine protection performance equivalent to the higher number (usually 40 in the case of 0W oils)

Because flow rates are dependent on engine design it is essential to use ONLY oil with weights and specifications recommended by the engine manufacturer, unless you are an expert yourself with appropriate test facilities. If Alfa is now "recommending" 10W 60 all they are saying is this works. The specification for the oil issued when the engine was sold is still valid.

I use 5W 50 synthetic year round, as 10W 40 is NLA in my market and our winters are damned cold eh?

Michael Smith
91 164L White
150,000km original owner

While I cannot justify using synthetic oil in my 91S because it has always used somewhere around a qt per 500 miles in city driving (and with 125,000 miles, 20w-50 is good enough), the 94 LS uses none that I can tell, so it will be getting 10w/15w-50 synthetic come the next oil change, my feeling that the cold 20w of 20w-50 may be just on the thick side for the higher revving 24v engine, although I do carefully warm the engine up before we drive anywhere.

Del

Seattle

Oil pressure directly relates to 'flow rate'. If your pressure is too low (below 15psi at idle); flow of oil across the bearing surfaces may be inadequate. If the viscosity is abnormally high, your pressure will be higher but the flow may be reduced due to increased friction (as in the condition of a cold engine/oil).

>Required oil pressure is a function of flow requirements.
>Low or high pressure is not the issue, quantity and rate of
>flow are the key issues. The oil pump has to generate enough
>oil pressure to deliver sufficient oil through the bearing
>surfaces to keep the oil cool enough so that it doesn't
>break down.

I agree with the first two sencences; but I would make the following change (in bold) to your final statement:

"The oil pump has to generate enough oil FLOW to deliver sufficient oil through bearing surfaces to keep oil cool enough so it does not break down."

If your pressure increases with heavier oil; the flow may or may-not decrease, but certainly the flow will not be increased. If the flow stays the same or decreases; the result will be increased friction and increased temperature rise of the oil as it flows across the journal bearing.

That wedge requires oil with certain viscosity
>characteristics to maintain the film. Excessive heat
>eventually causes components of the oil to flash off and if
>severe enough the film breaks down and bearing failure
>ensues very quickly. If it weren't for the heat the bearings
>could have a sealed oil or grease supply as many slow speed
>cool running bearings do. The flow of oil in an engine is
>essential to keep the oil in the bearing cool enough to
>maintain that wedge.
>

Yes; that's why it confuses me why you would want higher viscosity; when the higher viscosity increases pressure (potentially reducing flow), and increases friction (thereby increasing heat produced). Heat generated by viscous flow at the bearing surfaces is not trivial; it can be quite high from the entry port to the outer edge of the journal.

>So, heavier visocity oil is really oil that resists film
>breakdown better than lower viscosity oil.

I don't agree; the viscosity a flow property, not a 'boiling point' as you put it (in reference to 'flash-point' etc). I think you are confusing the terms "viscosity" and "thermal-breakdown".

But, the number
>is only one factor. Synthetic oils are much more resistant
>to film breakdown than conventional oils, generally because
>they have less volatile components and more of the long
>chains that preserve oil film. This is why lower viscosity
>synthetic oils give equal or better protection than heavier
>conventional oils.

So synthetics are more resistant to thermal breakdown; but viscosity properties should be fairly similar among like-weights. The old Mobil-1 marketing demo was heating their oil up to 500F would cause no burning; while the non-Synth oils would smoke and burn.

>
>That 60 number is the hot number and is not a measure of
>actual viscosity but a performance number. For multi grade
>oils the numbers refer to the fact that the hot performance
>of the oil is equivalent to a single grade conventional oil
>with that number.

Yes; it is that the slope of the viscosity decrease across the temperature range is reduced for the multi-weights over the single weights. At temps around 200F the 10/60 has a viscosity similar to single wieght 60wt.

The W or Winter number indicates that the
>flow characteristics of the oil are equivalent to a single
>grade conventional oil with that number, at the specified
>winter temperature. The W number does NOT refer to the
>ability of that oil to protect the engine, only the higher
>number does that.
>
Lower number is the "cold-oil" number, IE the viscosity when you start the engine on a cold morning. And cold 10-wt oil is WAY more viscous than warm 50-wt. That's why all of the engine wear occurs when the engine is cold and warming up. The oil is just too damn thick; the friction is high and the flow is low.

>Obviously, no one wants a 0W weight single grade oil in
>their crankcase, but if it is a multi grade and especially a
>synthetic multi grade it will have cold weather viscosity
>similar to a 0W conventional oil but the engine protection
>performance equivalent to the higher number (usually 40 in
>the case of 0W oils)
>
>Because flow rates are dependent on engine design it is
>essential to use ONLY oil with weights and specifications
>recommended by the engine manufacturer, unless you are an
>expert yourself with appropriate test facilities. If Alfa is
>now "recommending" 10W 60 all they are saying is this works.
>The specification for the oil issued when the engine was
>sold is still valid.
>
I agree; but I question why 10-60 now after all of these years? Is this in reference to the late model V-6 engines (past our cars, and in recent years) or early model GTV-6 engines or ?? Surely it is not due to the sudden revalaton that the oil weight that was originally specified was too low; nor that the cars are lunching bearings while under warranty (warranties are expiered long ago on our 164s and GTV-6's). I wonder if this is some confusion with the new "GTV" V-6 and the older GTV-6.

>I use 5W 50 synthetic year round, as 10W 40 is NLA in my
>market and our winters are damned cold eh?

Hard to find 5-50 out here in CA; but it would be a good choice IMHO.

Del

Seattle

http://www.alfaholics.com/racing_and_competition_corner/performance_and_racing_parts/document_31_82.php

Ciao, Alfisto Steve
Virginia Beach, VA

91 White 164B Originale
91 Black 164L Alfa Rescue Society project
91 Green 164L Another Rescue Project (My son's)

A day without an Alfa whine is like a day without sunshine

Sure was sad to see that picture of the silver GT Junior bought from the breakers. Looked like it had been rotting away in that shed for years. As a point of contrast, I saw a perfectly beautiful 60's GTV at the dealer last week, in for service. Not a flaw in it.

I remember seeing a very complete straight and clean black mid 60's 1600 spider in a local wrecking yard that was missing only the engine. The yard personel said that something went wrong with the engine, so the owner (a older woman, I think she told them she didn't know anything about those cars, so take it away) just had it hauled away to the yard. The title was turned in, and the car was being parted, the engine first to go, as it was evidently just a simple fix. Can you believe it?

I almost bought it to put an engine it, but I had just rebuilt my Downton/Austin Cooper S for the umpteenth time, and was down on available cash. Talk about unreliable, Alfa owners have NO idea what that means until they've owned something like that. It ate differentials and rod bearings for lunch, every 5000 miles.

Del

Seattle

In European Owner's Manual on page 268 (chapter Service Station) it's clearly stated that in all pertol versions "For sports drvivng we recommend Selenia Racing 10W/60, synthetic oil"

That's what I use

Best regards,

Tom

Warsaw, Poland

Can someone scan the page into the forum?

Del

Seattle

Del,

I forget to take the manual to my office where I can scan it. I'll do it tomorow and send you an e-mail.

Best regards,

Tom

Del

Seattle

Just my experience

Dave

It's amazing that few people know about CH-4. I'm wondering if your tensioner leaks from the CH-4? Thanks.

Almost all modern name brand car oils contain sufficient detergents to keep a gasoline engine clean with normal oil changes. I've read that one reason diesels use something like CH-4/CI-4 with it's very high detergent/additive ratio is that truck operators and others who use diesels run many more miles/hours between changes, the CH-4/CI-4 lubricants being specifically formulated to counter the high sulfur content in diesel fuels, and to hold in suspension the high levels of diesel soot found in the lubricant (common in diesel engines, esp those designed for very low emmisions) and allow it to pass through the filter without clogging. This can enable operators to go many more miles/hours without changes. Some go as high as 500k miles between changes using modified oil systems (burn a little, automatically bleed in a little new) since the lubricant itself doesn't degrade much except at extreme high temps, but gets contaminated with blowby debris and liquids.

If you change your automobile oil somewhere between 3k-7k miles, you are doing about as good as it gets for normal usage; however, there appears to be nothing that would prevent you from using CH-4/CI-4 in your gasoline engine, except for the fact that there are apparently no 50w diesel lubricants being made meeting the CH-4/CI-4 requirements, only 5w-30, 10w-30, 10w-40, 15w-40, etc.

Almost all diesel lubricants are synthetic, and cost about 50% more than auto synthetics. You are paying for additives that you most likely don't need for a gasoline engine. The diesel lubricants are also supposed to reduce engine metal to metal scuffing and other wear indications, as well as reducing varnish build-ups, etc, but I don't know whether or not that is a function of the lubricant being synthetic or because of the additional additives, I strongly suspect the former. Some manufacturers of synthetic lubricants advertise that their product meet the requirements of both gasoline and diesel lubricants. You would have to read the codes on the label of the container.

Del

Seattle

As for expense I buy my oil form the local shel distrubutor since it is the only place that sells it retail. I've been paying about $70 for 6 gallons. That's much cheaper that mobile 1 it's $20/gallon.

Tim Annett
1995 164 Quadrifoglio
Laverdas!

Tim Annett
1995 164 Quadrifoglio
Laverdas!

Del

Seattle

Mike