jetlagjim

Any problem with mixing multi viscosity Mobil 1 oil such as 5w 30 with 0w 30 in my 996 crankcase?

Mark I

Nothing wrong with mixing, but this time of year in NC, you should be going to 5W40 (some prefer 0W40) or even 5W50, depending on your driving plans. Let's end this here before it turns into another oil thread.

logray

You shouldn't use a 30 weight multi grade oil. Not designed for the car.

Use a 40 weight oil and mix away to your hearts content.

Or better yet, just change the oil with the same approved grade. i.e. 0w40 or 5w40.

kromdom

curious why this idea came up in your mind? leftovers from other cars?

SSST

Personally, I don't like mixing oils. I'm not sure there is any scientific basis for that, but I can't see any upside to it and why take the risk.

Agree that 30wt is not a good choice for these cars.

Macster

First 5w-30 is not any viscosity approved for use in your car's engine. Approved I might add by the maker of the car, and the engine: Porsche.

Second, while Porsche says that when topping up approved oils can be mixed when possible the same oil should be used that was used for the last oil change/fill.

Now if you want to change to another approved oil at the next change there is no need to 'flush' the engine of the old oil. All approved oils are miscible.

You have a good selection of 0w-40, 5w-40 oils, and even at least one 5w-50 oil. I fail to see what you hope or expect to achieve over and above oil engineers/chemists have even if you confined yourself to approved oils.

Sincerely,

Macster.