Combining Oil Viscosities??

[ruby911]

This may well be a really dumb question, but what would be the impact of topping off oil that is filled with 20W50 with something other. Obviously, this is not ideal, but if in a pinch and had to do it, is there any residual effects?

[wowzer911]

I think that you would want to use the same brand and formula at the very least to help assure the two will mix.

[twistoffat]

It won´t effect the motor. Its would be ideal to keep to the oil recommended for you motor but a blend is better than too much or little of any oil. The viscosity number represent cold and warm characteristics of the particular oil used. Topping up 20 W 40 with 10 W 40 will have no negative effect. A regular oil change is the most important part of motor care

[carnutzzz]

Originally Posted by ruby911

This may well be a really dumb question, but what would be the impact of topping off oil that is filled with 20W50 with something other. Obviously, this is not ideal, but if in a pinch and had to do it, is there any residual effects?

Nope- very safe. Especially in a 911 where you're mixing into a lot of volume.

[ruby911]

Thanks Paul

[Por_sha911]

Per Brad Penn Rep: If you put in 5 qts 20/50 and 5 qts 10/40. You actually have 15/45 oil. Simple math.

[Kraftwerk]

It can't hurt every so often.