OIL FOR 986 BOXSTER
 

My car is running Mobil 0W40 synthetic oil does it matter if i change it to Mobil 5W40 synthetic oil .

Do you drive it in the winter? Even then you likely won't notice a difference.

There are a number of Porsche approved 5w-40 oils. (My local Porsche dealer service department would print out a copy of the Porsche approved oils list for me every so often but I don't have a current one to share.) If for some reason you want to use one there's no real reason not to -- and all approved oils are miscible and the engine does not require a flush to switch from one approved oil to another -- other than Porsche says to use 0w-40 in cold temperatures and gives -25C as the threshold. Really though I'd run 0w-40 if the temperature got below 32F but that's just me.

Do your engine a favor and search the internet for the answer and read as much as you can from reliable sources.

What climate do you live in? Mobil 5W50 would be a great choice (except winter, use 0W40 for winter season). It's A40 Porsche approved, and easy to buy on sale about 4 times a year at Napa for $6/quart. Couple times a year, you can double dip with the Mobil $2/quart rebate.

Funny. Apparently in regard to which oils to use with its engines Porsche and its oil list is not a reliable source.

If one strays from the Porsche approved oil list he can use anything to justify his selection of oil. Thus oil selection is based on myth, hearsay, rumor and innuendo and one's current definition of which source of this is "reliable".

When life gives you a can of worms.... go fishing.

Since are cars are really just low flying airplanes, I use this one:

https://cimg4.ibsrv.net/gimg/rennlis...e3c7933d78.jpg

Why not just use what's recommended in the Manuel? Why do you want to change?