WCE

As a past 996TT owner, I just wanted to put out there that nearly every other manufacturer recommends 5W-40 not 0W-40. While Porsche says it is good for "all temps", they also say 5W-40 is OK above -13 F, which is most every US location especially for a garaged car. The slightly heavier weight oil will lower oil consumption and on hot days at the track, that water weight 0W-40 always concerned me! I know in theory the high end "40" number means they should be the same, but overall the viscosity will be higher. Since 0W-40 can be hard to find, there's another reason to give it up - hope this helps!

vr4henry

I've really liked the mobil1 5w50. Much less oil consumption in my experience of two 996TTs

SSST

It sounds like someone is bored and wants to stir up trouble for the weekend.

Macster

I've run 5w-50 in my 03 Turbo (and 02 Boxster now with over 265K miles) and I can't say I noticed any difference in oil consumption to what it is with 0w-40 in the engine.

What I do notice is oil consumption is affected by how I drive the car. If I really push the car hard, drive it in a spirited manner on say a back road with lots of high rpms the oil consumption goes up. And this is with either oil in the engine. The oil level can drop a bar easy after a 15 to 30 minute hard run.

But with reasonable driving the Turbo (or Boxster) engine uses less than a quart of oil in 5K miles.

The only difference I've noticed is the hot oil pressure at idle was a bit higher with 5w-50 compared to what it was with 0w-40 in the engine.

Not a lot. Just enough to notice the oil pressure gage needle is positioned a bit lower running 0w-40 vs. 5w-50. Say if with 5w-50 the needle is at 2 bar, with 0w-40 the needle is maybe a needle width under 2 bar, call it 1.8(?) bar.

Oh, and this last 5K mile oil change running 0w-40 the tech reported the signs of a suspected leaky RMS have gone away. I really think this "leak" was due to me inadvertently running the oil for 10K miles vs. the usual 5K miles a few oil change intervals back. Family/personal business had me so busy and distracted I simply lost track of the miles and ran the oil 10K miles vs. the usual 5K miles.

I'm debating switching back to 5w-50 for the summer. The Mobil oil distributor relocated from just a few blocks away from my office in Hayward CA to down in Union City CA so I can't as quickly run by on my lunch break and grab some cases of 5w-50 oil. The dealer's price for Mobil 1 0w-40 out of the dispensing gun is quite reasonable, priced less per quart than I can buy the stuff retail even from the distributor so there's no savings to be had there either.

PAULUNM

BUT IF PORSCHE SAYS IT'S OK IT MUST BE!

Kevin

WCE, there have been many oil threads. Others have paved the way to recommend steping up to a 5W oil.. If you have intermediate shaft noise.. A switch to 5W40 Mobil TDT or Shell Rotella T6 is a great choice.

"02996ttx50

... and in other mobil one 0-40 news.. this miracle viscosity has now slowed macster's leaking rms! is there nothing this oil can't do!? lol

King_James

Sorry guys, I'm not an oil expert but I do read a few things here and there. A 5w-40 and 0w-40 have the same weight when warmed up, your oil consumption will be exactly the same when warm.

Oil today is multigrade, not single weight like 50 years ago. This means the oil falls in to 2 viscosity grades, ie 0w-40 or 5w-50 as we're discussing here. Multigrades were developed for thinner oils in the summer and thicker for the winter. The W in the oil description stands for Winter and means the specific weight when cold vs. warm.

The 40 in a 0w-40 simply means that the oil must fall within certain viscosity limits at 100 degC. This is a fixed limit and all oils that end in 40 must achieve these limits. Once again the lower the number the thinner the oil, a 40 oil is thinner than a 50 oil at 100 degC etc.

If you're experiencing oil consumption and thinking a 5w-40 will solve your problem, unless the burning is all at startup it won't make any difference. A 5w-50 will stop oil burning but remember it's 25% heavier when warm than a 40 weight oil is. Porsche recommends a 0w-40 oil for the 996t. Many people move to different weights and say there isn't an issue. I'm not really here to argue the best oil, that's beyond my knowledge level.

PAULUNM

Porsche also has 5w40 and 5w50 on the official approved oil list...

0w40 is the most common fill in the US. Most dealers in Europe use 5w40 or 5w50. And our temps here in the us tend to be a bit higher than Northern Europe.

King_James

That's because Castrol sponsored the Porsche racing team and they make 5w-40 so the Mobile1 / Porsche pact is officially over.

Not sure I would be running oil that's 25% heavier (5w-50) in my car just to stop filling it up a bit once a month, but to each their own.

SSST

I've been running M1 5-40 TDT for three cycles now. The motor runs very smooth and quiet with this oil through the full 5k miles. It had 0-40 when I first bought it and the IMS noise is significantly lower with the 5-40 TDT.

When i first got it Mrs. SSST said it sounded like I needed a valve job. After to oil change, she asked when I got the valve job. LOL. She's a Chevy small block kind of girl. But she's coming around.

Kevin

One thing that folks need to realize is that every oil is different. New out of the bottle it might be rated at a 40 weight or 50 weight. But once warm and run a few miles you will see the the 100C testing numbers changing between oils. Motul and Mobil have different numbers at 100C viscosity when run "X" hours. Our engines are hard on oils. The multiple geared pumps shear the oil. You do not want the oil to shear to a 30 weight>>which does happen.

PAULUNM

You obviously have no idea what you are talking about

http://www.pedrosgarage.com/Site_3/P...oved_Oils.html

Macster

What slowed the oil leak was getting back to a 5K mile oil change interval.

As I covered in my post I let the car go 10K miles with 5w-50 (my "summer" oil) due to being quite distracted with more pressing issues.

During the oil change the tech as is his habit inspected the car and spotted what he believes is an RMS leak. With me under the car with my own flashlight he went over the various leak sources in that area and eliminated them and this pretty much puts the oil leak under the bell housing which limits the possible leak sources though of course we won't know for sure until such time as the tranny is dropped and the leaking area exposed.

At any rate, the leak wasn't bad and the tech advised a wait and see course of action.

The oil was changed from 5w-50 to 0w-40 (my "winter" oil) and 5K miles passed with no easily visible signs the oil leak was getting any worse.

Then it was time for another 5K mile oil change. Again the tech checked the car over and the oil leak has appeared to subsided.

This is not due to some magical property of 0w-40 oil but any appropriate oil would have probably had the same result. Fresh oil is more viscous -- not contaminated with unburned fuel and water -- thus a marginal seal is less likely to seep with this contaminated oil drained away and replaced with fresh oil.

It is this that accounts for, as I have observed more times than I can remember over the years (and with my Porsches alone over 360K miles of driving) and after doing a number of oil changes myself, the engine is markedly quieter after an oil change.

There is no problem with Mobil 1 0w-40 oil or any of the approved oils. The problem is with all the cockamamie oil experts and in their unscientific opinion a better oil is needed then selecting this oil based on in the context of this thread that 5w-40 oil is "thicker" than 0w-40 oil, for instance, and switching to such an oil will address some imagined oil problem.

I will add that if someone wants to use an approved 5w-40 oil instead of 0w-40 oil there's nothing I can see wrong with that.

If someone wants to step off the oil reservation and run an unapproved oil then it matters no one whit upon what basis they chose this oil. Pulling an oil name out of a hat would be as scientific as any other method.

Why some owners are willing to gamble their engines on testing off the reservation oils is a puzzle to me.

What saves these people is for the most part the oil is good enough (for a while) and because nothing bad happens right away this is used to confirm their choice was right.

And it will be. For a while.

"02996ttx50

so, for this i take it you've surmised that the relative increase in viscosity(?!) owing to it being "fresher" at 5k miles vs 10 k miles has somehow slowed the ( possible ) rms leak? ( bell housing, sounds like rms area to me? ).. i dunno, man... but ok.

while rms leaks on these cars can be very slow ( ask me how i know.. ) i would be very dubious as to the veracity of your conclusion. but if it's slowed down ( the leak ) i suppose that's all that matters. i know i'm not going in there until i have to lol )

ps.. i say 5/40 is fine for CA weather/conditions.. i would've switched this time to 5/40 but my ecs tune kit came with 0/40 and i neglected to ask for the heavier weight. no big deal. car's been running 0/40 and 5/40 for a decade. no problems. hmm... maybe i'll switch again to 5/40 and maybe my rms will stop leaking.

ps.. "off the reservation oils". love it. i'd like to use that with attribution, but i can't imagine another conversation in which i might... but