nycebo

First, the preface: currently, I'm running Mobil SuperSyn 15W-50 in my car even though I live in New York City. Nonetheless, I have been thinking about switching to Castrol Syntec 5W-50 when I swap the oil next time.

So, I'm reading the Joel Reiser's tech letters over at PCA and thought to stir up a pile of 'oil' again. I know that 1999Porsche has been adamant about 0W-40 not being up to the challenge of protecting the engine when it gets hot, but the cold temp concerns on the hydraulic lifters seems very reasonable. Of course, the point about the engineers lightening the oil as a compromise is a little worrisome too, as in thicker oil is better for the engine but let's not sacrifice our whole budget by building a second reservoir for the lifters. Read on....what do you guys thing? It certainly buoys the case for using 5W-50 at least, yes?

Here's some snippets from the PCA site:

wingless

The Mobil 0W-40 is approved by Porsche and carries both the MB 229.3 and the better 229.5 approvals.

At this point I would not use any oil that does not contain the MB 229.5 approval.

Mother

Yes, you are opening another can of oil here! If you are not having any problems with the the oil you are using now then switching to 5 - 50w Castrol I don't think will change much. I am a big fan of castrol and used it on all my cars here in Arizona and it seems to hold up to the hot temps very well.

nycebo

There were a ton of posts in the past where some guys highly stressed the importance of having the 50 up top instead of just the 40, particularly on those hot summer days. Clearly, Porsche recommends the 0W-40, but I wonder if, on appeasing the hydraulic lifters with a thinner oil at startup, they aren't sacrificing a little bit of engine durability. As Mother said, I think Castrol seems the PERFECT compromise.

Ah, what a big can of 'oil' it is....

Tool Pants

Nuts.

1999Porsche911

Hydraulic Valves lifters always have a small little orifice, as Joel calls it. How else would you get any bleed down to constantly adjust for play in the tappett. This orifice is to allow oil to escape and not a feed to the tappet. That is why the thinner the oil you use, the more noise you get at startup in warmer climates. In extremely cold weather, even the thinner oil may not bleed out the hole completely. The thinner oil is allowed to drain from the oil chamber while the engine sits, providing little to no oil protection at startup. The noise you are hearing is metal to metal.

Hydraulic valve trains have existed for decades and have shown no unusual wear using 15W50. Why doesn't Joel make any comment on what the 0W40 oil does to the engine when it is at a temperature of 220F+? Engine oil protection is not one demensional.

Furthermore, at startup, it is more important to have shear protection than oil pressure (but I would rather have both). Shear protection is the film of oil between metal parts, such as the plain bearings. If this protection is too thin (as I contend it is with 0W40 oil), the high spots on the bearings will not be protected reducing the life of the engine.

Mother

I have a feeling that Tool Pants was to embarresed to show the can of "SLICK" not in the picture. Besides you ain't liven till you put 50/50 ant-freeze in your tranny.

Chris 996

Maybe that is what Bob uses too.............

nycebo

You always make good sense, brother. And frankly, the way I drive the car when it IS warmed up, you have definitely convinced me before (on 6speed where you were addressing this before) that having the 50 up top is very important.

1999Porsche911

Here is another reason why you shouldn't bother with the PCA site.

http://www.pca.org/tech/tech_qa_question.asp?id={C1742344-F063-4DA0-80CA-1AA671FFED0A}

This guy really should not be replying to people's queston if he is going to be as wrong as he usually is. IF, and I stress IF...the tapping is coming from the lifters, it is because the lifter is bleeding down too fast and NOT because oil is not getting into the lifter barrel. Therefore, 0W40 would be the worse thing you could do to your engine.

He should do a little research and see if he can determine just exactly what the difference is in flow rate for a 0W40 and a 15W50 when the oil temp is in excess of 220F. Does he even know how hot the 3.4 engine runs in city driving? Does he know that even the coolant temp will regularly exceed 220F while driving around town? Has he ever measured the almost immeasurale oil temps at specific spots in the oil system? What's the highest spot temperature reached? Is it 300F or 400F or maybe higher?

If you drive your car like a normal daily driver, seldom taking it to the limits or into the higher Rpm's, you may not see a difference in the engine wear during the life of the car. However, for those of us that drive to the extreme and would like our engines to still have tight tolerances and crisp performance at 150,000 miles, you are best served by replacing your 0W40 with a higher viscosity. This is even more critical on a forced induction engine and with engines that sit for long periods of time between starts..

It's really not rocket science. The fact is that a 15W50 oil gives you the same protection at 15F as does a 0W40 oil, yet gives you better protection when the oil reaches operating temperature.

bet

1999Porche911,

What do you think of the Castrol 5w-50? I see you are in Chicago...do you drive your car daily in the winter? If so what oil do you use in the winter?

1999Porsche911

I use the castrol or mobil. Currently running Mobil SUV 5W40 for the winter. 15W50 in the summer. 5W50 is ok too.

LVDell

I have a 2 oil change schedule now:

0W-40 in the winter months (late OCT thru beginning of March)
15W-50 for my DE season (beginning of March thru late October).

nycebo

I found an oil viscosity chart that drew my attention to something that I had not noticed before. The chart mentions a level of viscosity needed when outside temps 'consistently' fall at the demarcated level. As such, I can't say that even here in NYC temps consistently stay at 10 deg F. As such, 1999's concern that high temps are the greater concern seems pretty well warranted. I definitely think that a 5W-50 has us best protected and am very leary to go the 0W level, particularly since my car is garaged.

SPR

Interesting I thought that Porsche went 0 weight for the lifter bleed down. I would think that tappet wear is more of a concern than overall wear from the different weights? I don't know if it's simular, but I have seen how quickly and how much wear can occur when lash is not set right on a cam.