Luis de Prat

This subject has probably been beaten to death, but with the new reformulation of the most popular brands including Mobil1 to the controversial "SM/CJ standard," apparently lower in engine antiwear additive ZDDP, the question has become pertinent.

I use a multigrade version of Mobil1 sold in Europe and Canada, the 5W-50 Rally Formula. It's SL/CF rated, so in theory the ZDDP level should be OK.

Jason Judd

I'm using Mobil 1 15W/50...pretty straight forward.

Richard C

Me too.

Luis de Prat

I believe the Mobil1 15W-50 is now SM/CJ rated, which means the ZDDP levels are significantly lower.

Not sure this matters to you, but I thought I'd mention it since the 911 people are up in arms about it and have switched to other products with the former SJ or SL/CF formulation.

grants_968

Mobil 1 0W-40

RajDatta

Mobil1 15W50 on both cars.
Raj

PorscheDude1

Royal Purple 10W40 winter
Royal Purple 20W40 summer

rob76turbo

Redline 20W-50 for me. Hey it is expensive, but it is good stuff.

FRporscheman

Mobil is infamous for changing its formula a lot especially back when they merged with Exxon. History has shown that while their changes usually bring a not-awesome oil, after a while things get sorted out and what they put on the shelves is once again superior.

I use valvoline conventional, but after the rebuild i will use valvoline synpower.

H2

+1

H2

Lemming

Rotella T 15W-40. Changed after every track weekend in the Frankencar, every 6 months for the DD.

rdhayward

Is there some really compelling reason you guys don't use the factory-recommended 10W-30? Didn't Porsche know what they were doing?

I have an uncle who was a petroleum chemical engineer and retired from Exxon as VP of their Performance Products Division. He advises using what the manufacturer recommends, and that synthetic oils are very much a consumer-driven product, that synthetic oil is not cost-effective for most vehicles though it is understandable that a high-performance car owner would prefer it.

That said, here's a link that I often advise people to read when the issue of motor oil arises:

http://www.boss302.com/oil.htm

Jason Judd

"Is there some really compelling reason you guys don't use the factory-recommended 10W-30? Didn't Porsche know what they were doing?"
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I think that most of us, who have switched to a 50 weight oil, have done so because we track/race our cars.

I think the factory-reccommended 10W-30 is for a daily driver; which see different conditions.

968workaholic

Mobil one has lowered their ZDDP levels a ton. The reason being is that these chemicles cause the cat to wear out sooner. So the EPA gets involved and all but a few companies lower the ZDDP levels. Now ZDDP is a chemicle that acts as a high pressure agent, helping the oil to stick to the lifters when the cam is trying to push it out. I have seen a few cams that have scored on the tops of the lobes because of this. Now the cams had some mileage on them, but it was a select few not most that had shown this. Royal Purple and Red Line are the only two that I know of that have kept the ZDDP levels the same. The alternative is to buy an additive that has ZDDP in it. It probably won't effect the daily driver, but it can't hurt to have a fortifier of some type in their oil.

Red Line 15-50 synthetic is what we use

Luis de Prat

True, but I understand this also shortens the drain interval significantly, making the use of a full synthetic for durability reasons a moot point.

For that matter, you might as well use a high quality dino oil that's SJ rated with the desirable ZDDP level, and change every 3000 miles instead of the 6250 factory recommended interval. No?