Correct oil application?

[JohnW]

Last night I spent about 2-3 hours reading over the forum after doing several searches. My intent is to improve what I have been doing, but since I have daily drivers I am not looking to go way over board.

If anyone would care to respond I would be grateful.

I have a 2001 Jetta with a VR6 (20K miles) and a 2001 GMC C3 with a 6.0L (15K miles). I do my own oil changes and started at about 500 miles on each one using Valvoline full syn. I did changes at 1K and 3K also and lately have been doing a 5K interval. They may see a couple of 20 degree days a year if I go up skiing (otherwise it is a garage in the 40's.) The truck spends some time in the summer pulling my 3500lb ski boat with temps never exceeding 100 degrees.

After reading over the forums I have decided to change brands. I do not desire to get into oil sampling (although I have always been curious about my engines.) I wish to continue with my 5k oil changes (which is just 2x/yr) and despite some added cost, I will definitely run a full synthetic. Which commonly available synthetic would be correct for my application?

 

[TooSlick]

John,

Given that both these vehicles are garaged, I'd run the M1, 10w-30 in both. The 10w-30 Supersyn has impressed me the most so far of all their grades, given the oil analysis results I've seen. Even though the 0w-40 is marketed as their European formula and meets ACEA A3/B4, I see no reason to use it over the 10w-30 in a new VW or Audi engine. This rec. is also based on 22 years of experience running synlubes in VW/Audi engines, starting with a 1978 VW Dasher.

The VR-6 engines tend to run hot and using a more viscous oil will only make them run even hotter. If you go to the VW Vortex, you will find folks switching from the M1, 15w-50 specifically for this reason.

As I recall, VW is now recommending 10k change intervals for the VR-6 engines, but I'd probably shorten that to 5000 miles w/ Mobil 1, given how hot they run.

 

[JohnW]

TooSlick -- Funny you should mention VW Vortex. When we bought the Jetta about two years ago I was keeping up with the forums there and several people with VR6s were reporting their oil analysis results. The Valvoline seemed to be giving better results than M1, thus my use of Valvoline rather than M1. With my mild climate conditions I have always tended to run my viscosity numbers closer together and was pleased to read on this web site that this can be a good thing! John

 

[Al]

Welcome to the board. Mobil 1 10W-30 is probably the most available. 5K is somewhat of an overkill but it's your call. I really don't know what grade your VW requires. If you need heavier than the 10W-30 you could go with Delvac 1 or mix with some 15W-50.

 

[Dr. T]

I agree completely with G-Man II. 0-40 for the VW and 10-30 for the GMC.

TooSlick, what do you mean by "using a more viscous oil will only make them run even hotter" and "If you go to the VW Vortex, you will find folks switching from the M1, 15w-50 specifically for this reason"...right after you recommend a 10-30. So, why then wouldn't you recommend the 0-40?

 

[Ken2]

Don't forget Schaeffer's #703 10W-30, also rated ACEA A3, and priced below Mobil 1.


Ken

 

[JohnW]

Thx for all the input. I am going to seriously consider the Schaeffer's. If I understand synthetics correctly one of the benefits is better residual film lubrication for cold start ups before the oil pressure really kicks in. John

 

[G-MAN]

Given your criteria, Mobil 1 is without a doubt the oil you want: 0w40 in the VW and 5w30 or 10w30 in your GMC truck. 5000 mile drain intervals would be no problem for these oils.

 

[Patman]

quote:

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Originally posted by JohnW:
Thx for all the input. I am going to seriously consider the Schaeffer's. If I understand synthetics correctly one of the benefits is better residual film lubrication for cold start ups before the oil pressure really kicks in. John

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Actually you can get that protection with any oil that contains moly in it, even if it's not synthetic. Moly bonds to the metal to provide a layer of protection for cold starts. All of Schaeffer's oils contain roughly the same level of moly, even the 100% mineral oil they sell.

[ January 14, 2003, 06:32 AM: Message edited by: Patman ]

 

[Dr. T]

The bottom line is it's the engine's cooling system that is responsible for cooling the engine, not the oil...this is just a secondary function. Oil's primary function is to lubricate the engine and it's obvious that a lot of times (not always) a 20 or 30 weight won't cut it or else nobody would have sludge...because remember, you said "the thin stuff flows the heat away!"

The truth is it's so **** hot in certain areas that you need an oil with some cohones so that it doesn't end up scortched on the bearings, etc. BEFORE it can even takes away the "heat"....and it ain't flash point that's for sure...although the flash point on WD-40 can't be that high..

 

[G-MAN]

quote:

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Originally posted by TooSlick:
I also like the idea of using an oil whose properties remain stable over long change intervals. A 0w-40 will quickly degrade to a 5w-40 and then to a 10w-30 as it shears - but you'll have a 10w-30 full of degraded polymer. By contrast, a 10w-30/15w-40/20w-50 will maintain its original physical properties for a very long time, since these synthetic grades use little or no VI modifier. VI modifiers are polymeric thickeners and don't do all that much for lubrication. So if you have 10%-15% VI modifier in a 0w-40 or 5w-50 grade, you have to reduce the lubricating basestock by that same amount.

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There is some pretty good anecdotal evidence (as well as what was stated in the Mobil SAE paper on synthetics and extended drains) that the 0wXX grades of Mobil 1 actually have LESS VI improver than the 5w30 and 10w30. The wide spread is accomplished primarily through the use of the unique blend of esters and PAOs in the base fluid. And as the SAE paper shows, the 0w30 and the 0w40 were the most shear stable grades. In addition, the 0w40 showed only a 17% increase in viscosity after a quadruple length Sequence IIIE test. (At the time of the test, the API SJ limit was 375% increase after 64 hours. The 0w40 had only increased 17% after 256 hours. I'd call that a "stay in grade oil.")

 

[TooSlick]

Dr T,

It is the viscosity of the oil at normal operating temp - the second number - that will determine how high your oil temps will run. A 40wt oil will run hotter than a 30wt and a 50wt will run hotter than a 40wt. Install an accurate oil temp gauge and run your own comparison tests - as I have done - and you will see this effect right away. If you want to see this dramatically illustrated, run a 0w-30 and 20w-50 back to back under the same conditions. If you went to an extremely thin oil - say a 5w-20 in a worn engine - you could generate more friction and heat through increased metal to metal contact, but that's very rare.

A good analogy is to compare the amount of energy it takes to stir a glass of water thickened with cornstarch, vs one filled with plain water. From basic thermodynamics, energy can be neither lost or gained. Therefore, the energy required to pump and shear a more viscous fluid generates heat. If you stir the thickened water with an electric mixer, you can actually heat it up simply by "intrafluid" friction.

The secondary reason why thinner oils run cooler is that they circulate more rapidly and transfer heat more effectively to the engine block.

I also like the idea of using an oil whose properties remain stable over long change intervals. A 0w-40 will quickly degrade to a 5w-40 and then to a 10w-30 as it shears - but you'll have a 10w-30 full of degraded polymer. By contrast, a 10w-30/15w-40/20w-50 will maintain its original physical properties for a very long time, since these synthetic grades use little or no VI modifier. VI modifiers are polymeric thickeners and don't do all that much for lubrication. So if you have 10%-15% VI modifier in a 0w-40 or 5w-50 grade, you have to reduce the lubricating basestock by that same amount.

Finally even with synthetic lubes, I believe there are benefits to using a thinner oil in cold weather and a thicker oil in hot weather. The idea of a 5w-50, "one size fits all" grade is appealing, but you rarely have an optimized lube situation this way.

 

[YZF150]

Hey, G-Man, point me to that paper, please.

 

[G-MAN]

quote:

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Originally posted by YZF150:
Hey, G-Man, point me to that paper, please.

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Send me a private message with your e-mail address and I'll e-mail you a copy of the paper. Otherwise, you can get it from www.sae.org for $10.00.

 

[jason07-1zzfe]

Hey TooSlick what happened to your post from yesterday about the volatility and IIIE test of 0w40? I thought it had some good info there.