I had an oil change today and they did not have enough 0w-40, so I figured why not try the 15w-50 Motul Competition 300V. The car seems to run strong and I can't really notice too much of a difference other than the oil pressure when idling is slightly around 2.25 after an extended drive, where as it used to be right at 1.5 when stopped.

Is this something to be concerned about? Could it possibly be better?

 

The higher viscosity of the 15W-50 will naturally cause a higher oil pressure. So that, in and of itself, isn't a worry.

FWIW, the 15W is too heavy for my taste for cooler/cold weather driving--I would only use something that thick for hot summers only. Also, if you have an '02 or newer 996, the VarioCam Plus may not work properly with the thicker oil and you'll get a CEL for your trouble.

If you're brave--or dreadfully bored--a search in here on "oil"...you'll fill several hours reading all manner of opinions about oil brand, weight, etc. Enjoy!

 

I have a '99 C2 3.4. I thought it would be okay to run this summer as the temps are typically anywhere from 75-100 deg, June through September. The car also sleeps in a garage.

I did some research and it looks as though Porsche rescinded it's statement in the owners manual of a 15w-50 being safe in ambient temps above 50 deg, but I would imagine this grade of Motul should be okay even at start-up?

 

Fyi: Motul 300v is racing oil and is not intended for long fill intervals. Use the 8100 x-cess/clean series 5-40 which use a different additive package.Your choice of oil and viscosity are not good for this application.

 

Couple of things to consider.

First Porsche does not support the mixing of approved and unapproved oils.

Porsche advises that when filling the engine the oil should not be mixed with other oils, even if they are approved oils.

The only time approved oils can be mixed is if the engine needs topping up or when the oil is being changed from one approved oil to another. There is no need in this case to flush the engine of the previous oil.

Next, a higher oil pressure may not be of any value. In fact it just wastes hp. And a higher oil pressure can raise the oil's temperature because the oil is experiencing more hydraulic friction from its higher viscosity so the oil at the critical bearing surfaces may be hotter than it would be otherwise and hotter oil may not protect the bearing surfaces as well.

Next the cam lobes are splashed lubricated from mainly the oil that comes out around the zero-lash lifter body. By running a thicker/heavier oil these may not be lubricated as well as they would with the right viscosity of oil in the engine.

You really ought to consider using the right oil and not mixing it with any other oils, approved or unapproved.


Sincerely,

Macster.

 

I really did not consider any of these things and trusted the shops judgement yesterday. I referenced the owners manual and it said 15-50 was okay above 50 deg and thought it should be okay. The oil pressure is now back to normal, but I will probably go back to an approved grade Tuesday.

Do you think an engine flush is now necessary?

 

15w-50 was approved but has been off the approved list for a while now. I ran it years ago in my 02 Boxster when it was approved. But I don't run it any longer.

You need to get an approved oils list from your dealer's service department if you want to to know all the oils you can select from. The latest I have is dated 4-2010 and the certifcate dates expire out in 2012 and 2013 so chances are there no more recent approved oils list.

There is no need to flush the engine. If you want to change the oil just drain it like you normally would then fill it with the proper amount of the oil you have.

Sure, draining the oil might be overkill and there'll be hundreds of posts from people who will report they've mixed every combination of oils under the sun and their engines are just fine, maybe better than they were, as their proof.

But if it were me and my engine I'd drain the oil and replace it with a proper oil. Consider the short time this oil was in the engine as an engine 'flush' of some kind. The oil that is left in the engine will be cleaner than the oil it replaced, so that's kind of side benefit from this.

Sincerely,

Macster.

 

Just change it...no drama. Btw if you want to stay w grade 5 Motul (mobil is grade 4) both of the oils I mentioned are Porsche approved and excellent. And some will say 5-40 is a better way to go anyway.

 

Thanks. I am going to give the 5w-40 a whirl. I know it may not be approved, but what do you think of Amsoil 5w-40 euro blend?

 

Hey guys

here in germany the Castrol Edge Formula 10W 60 is having alot of fans and supporters...most of the wellknown Tuners use this oil in their Cars...also in the Porsche 996 models like i do
Have never heard something bad about that oil.....

cheerio from Hamburg...

 

I like the 5W-40 choice. Among other things you won't have to change it for the winter unless "global warming" regularly reduces minimum temperatures in your area to -20 degrees .

As for brand--you'll be getting a full synthetic base oil with any 5W-40 and, IMHO either Grade 4 or Grade 5 synthetics are plenty fine. It's the additive package that makes all the difference. Your '99 was designed to run on API SH grade oils, whereas most automotive oils on the market today are API SL or SM. The newer API grades have lower concentrations of the inorganic additives that work really well in high temperature/high shear environments. There's a long write-up on oils on LN Engineering's website (https://www.lnengineering.com/oil).

FWIW, I have opted to blend Mobil1 0W-40 automotive oil and Mobil1 Racing 4T 10W-40 4-stroke motorcycle oil (which has higher additive levels) to obtain a 5W-40 oil with additive concentrations approximating those my '02 was designed to use. One could do this with Castrol and some other oils as well, but Mobil published enough information about their additive packages to calculate the blend's levels; Castrol is stingy when it comes to publishing data. Read the LN article and make your own, informed decision.

Good luck

 

Just as a rule I think it best to use an approved oil if you are under warranty

 

I simply do not understand what drives Porsche owners to be oil testers, to subject their engines to non-approved oils, to use their engines as an oil guinea pig running these various non-approved oils, or worse running some concoction of approved/non-approved or even 100% non-approved oils.

What is to be gained?

Also, an unapproved oil may not be on the list because the oil maker (and not Porsche) has decided the oil is not suitable, does not meet with the requirements that Porsche has set forth.

Anyhow, it is your car, and if you want to use an unapproved oil...

Sincerely,

Macster.