mixing 0w40 with 5w40

[gmk666]

Does anyone know if it is OK to top up one with the other? I want to stick with Mobil 1, but can't find any 5w40 anywhere.

[BliarOut]

The manual said:

Above -10 oC SAE 5W-30, 10W-30, 0W-40, 10W-40 and higher. Below -10 oC SAE 0W-30, 5W-30, 0W-40, 5W-40. Engine oils approved by Porsche -All oils on the Porsche approval list. - Oils of viscocity 0W-40, 5W-40, 10W-40 and higher if they comply with the ACEA A3 specification. - Oils of viscocity 0W-30, 5W-30, 10W-30 if they are included in the Porsche approval list.

If you mix a 0W - 40 in with a 5W - 40 it will be slightly thinner at cold start. Depends on how much you're adding of course.

[gmk666]

Thanks for that. Don't think I need to add too much, although this changes from day to day. It all depends on how the digital dipstick is feeling at the time.