I've gone through quite a bit of oil treads and it seems a lot of people use 0w40 or 5w40 weight synthetic oil, and in particular, mobil 1 because it's what porsche recommends. However, what I don't get is, why do so many owners use such a thin weight oil when the manual specifically says "Don't utilize thin oils for general use." (pg. 99) The thinnest oil the manual recommends is 5w30 and that's for ambient temperatures mostly lower than 14 F.

So it seems people listen to porsche about the brand of oil but not about the weight. Strange.

With this in mind, what weight oil should I use in my 993? I live in LA and temps don't drop below 50 F. Which in that case the manual recommends 10w40, 15w40, or 15w50. During the last oil change I put in castrol syntec 5w50, btw.

Thanks for any input!

 

What's this with all the controversial threads lately? 15w50.

 

Controversial? I was not aware...

 

Me neither,....

Jimmy:

Porsche makes some odd recommendations and some are based in expediency, not science or technology. Their insane oil change interval recommendations come to mind,.......

For an air-cooled engine being operated from 32 deg F to 120 deg F, we use Mobil 1 15w-50.

Ultra-wide viscosity oils such as 5w-50 oils do break down faster than narrower range ones do, so change it often if you use that stuff.

 

i was just at my shop (midwest eurosport, chicago area) and asked the same. they just filled my car w/m1 15-50 and not 0-40. being so close to winter and mine being an daily driver is asked about the 0-40. they said to stick with the 15-50. i'm figuring they know more than i do about this...though i wouldn't be the farm on it- i may be betting my 911 on it. i don't mean to sound 'flip' about it but, i think it's most important to make sure it has oil 0-40 better at start, 15-50 better when the car warms up, i think. fussing over the weight might just be fussing.

 

Steve,

Thanks for the insight. A lot of arguments I hear for a thin weight oil is the cold engine start-up issue. In your opinion, does the thinner weight oil, say 5w50, provide a significant advantage during start up over say a 15w50? Is 5w50 every 5,000 miles for daily "spirited" driving sufficient? Thanks again.

 

Hi.

I doubt there is much difference between the good brands at any level a none F1/racer person would notice. My indy shop puts 5w-50 in all the cars, all of them. I think they get a huge drum of the stuff frequently, and have never had any oil related problems. We get a good price on the oil for a shop price, basically the same as if we had bought it at Walmart +/- 2-5%. They did note that the 0w-40 was not around during the 993 years and think it might be too thin for that engine. Racer types get the 15w-50 or such.

Perhaps the most interesting factoid of the least value: my mechanic told me that Mobile 1 has the highest heat capacity, and when one gets burned with it - the damage is a whole lot worse than with Castrol Syntec. I have wondered if this impacted its use on air cooled cars either way.

Our other cars, both modern, water cooled, turbocharged or otherwise high end, European cars use 0w-40 for general use and get new oil every 7500 miles. The P car will get oil every 3500-5000k (no track time at all, and no hi revs until warm, etc.) or every 6 months, whichever comes first.


In the past on other cars, I have noticed more valve noice with 0w-40 than 5w-30 both mobile 1 (was a volvo S60T5). Scared me at first, but was told that it was "ok." Bascially, I'm sticking to either 5w-50 or 0w-40 for my cars...leaning to the former for the p car. It works. Why mess. If I move and the new shop swears by 0w-40, I'll be ok with that too.



jb

 

Just as a data point, Ferrari recommends 5W-40 for my 360. I think the industry in general is moving to lower weight oils to minimize wear on startup.

Gary

 

Jimmy:

A few points:

1) There is no question that a thinner oil flows more freely at temperatures below freezing so the question about which one to use is a question of "degrees".

2) Nobody should ever compare the oil's operating temperatures and loads in an air-cooled engine to a
water-cooled one; its apples & oranges. Oil temps stay very consistent in a water-cooled motor unlike the temps in the air-cooled one which reflects ambient temps and load. I would never operate an air-cooled engine at the track with anyone's 0w-40 or 5w-50,..........that later ultra-wide viscosity stuff requires a very good oil cooling system to maintain oil temps in the 190-200 deg F range.

Remember, that oil temp gauge only samples what is happening at one single point in the engine; its much hotter in other places.

 

Thanks for all the info guys.

Steve, again, thanks for the insight. I'll take all this into consideration. I think I may just go with 15w50 next time.