Jim Simone

I formerly used 15W50 Mobil 1 in my 1.8T and switched to the same weight in Redline. Afterwards, I talked to the Redline tech, who strongly advised me to go to a lighter weight oil, perferably 10W30.<p>I, too, was concerned with high temp performance (reached 105 deg.F last Summer)since I drive it hard and attend track events. Well, after some discussion with Larry V., I changed to the 10W30 and found the car to run *much* better - faster spool-up and better throttle response.<p>After running the car back to back with my wife this past weekend at the Las Vegas driving school, I'm also happy to report that the oil temp didn't increase any more than usual. If anything changed, it actually seemed to resist the increase until the engine had been running hard for a couple of hours. (The ambient temps at both events were about the same.)<p>FWIW,<br>Jim

Andy Hedin

All this talk has got me second guessing my decision to run 15W-50 Mobil-1 during the warmer months here in Philly...in fact I've got it in there right now. Anybody out there want to buy 10 qts of 15w-50 Mobil-1???<p>Andy Hedin<br>'97 1.8Tqms, Wett 1.0 Bar, ABT Filter, Euro Headlights...

Dave M

This has got me wondering, too. And I live in Texas! The specs for the 10w-30 and 15w-50 on the Mobil 1 www page seem fairly close to each other. Hmmm... I'm try'in to call my dealer right now, but no answer....<p>Dave M - '97 1.8tm

Dave M

Just talked to my service advisor. He feels that either the Mobil 1 10w-30 or 15w-50 would be acceptable here in Dallas in my 1.8t. FWIW, he did say that if it was his car, he would use the 15w-50. He offered no real hard advice either way, though.<p>Dave M - '97 1.8tm (still undecided on oil viscosity)

DaveL

That's what I've been using in Boston for 20k miles with no problems.

chrisd

I'm with Andy...feelin' a bit insecure about my oil choice...doesn't the manual suggest his is a good oil for higher temp climates?

ErikR

It certainly isn't going to hurt the car, we are talking (as usual) about a subtlety. You are way ahead by changing your oil and using syn.

Andy Hedin

First of all, 15W-50 is not classified as an "Energy conserving oil" as 5W-30, 5W-40, 10W-30 and 10W-40 are (at least they are listed like this in the Audi manual). From the graphic, those oils are good down to below -25 F or so. They appear to be good up to 100 F or so. Actually, just like the Audi dipstick, the manual is a little vague...the graphic stops at 100 degrees but it's shaped like an arrow which to me means that it's ok for even hotter temps.<p>Now, the graphic which includes 15W-50 has a sharp cutoff (not an arrow) at approx 5 degrees F which appears to be the lower limit of this viscosity. The upper end of the graphic goes higher than the 10W-30 graphic (the arrow goes to approx 105 degrees F).<p>So I'd say we're all OK to run 15W-50 in the hotter months and 10W-30 (or 5w-30) during the colder months. Personally, I think I'll just use up my remaining 15W-50 and then I'll pick up 10W-30 for summer, 5W-30 for winter....all Mobil-1 of course.<p>Andy Hedin

CharlieG

This is probably one of the more glaring differences (energy conserving or not) and a big reason why I will go with the 10W-30. Your climate (Philly) will be very similar to mine out here on the Island (LI, NY) and about tops here in the summer is middle 90's. I really won't be driving my car hard during the hottest part of the day anyway so 10W-30 looks like the best bet for me although I'm sure that the 15W-50 would be ok as well. I just don't want to leave the dino 5W-30 that the dealer used in for the summer so I'll drain it and replace with Mobil 1. <p>Thanks again for the lively discussion!<p>Charlie