Can you mix oils?

[pepsi_x]

Probably a silly question, but....

My Chim 500 had Castrol Formula RS 10/60 used on it's last service 4 months (and 3K miles) ago.

I accidently picked up Castrol Formula RS 0/40 at the weekend, can I put this in with what's already there, or would this be a bad idea?

Cheers in advance guys.

[plipton]

I wouldn't personally.

If the car needs 10-60 then mixing in 0-40 will alter the viscosoty of the oil. By how much depends on the ratio. This may be bad for the engine and could cause premature wear/seizure in extreme circumstances.

If you haven't opened it take it back and change it.

If you have opened it.....a vauluable lesson has been learned.

[the dodger]

Pepsi - don't do it. I won't kill the engine but it's not the same stuff. OK to use in an emergency (when you can't get anything else and have ran out) but best to stick to the same. 10w/- anything is better than 0w/- stuff.

[incorrigible]

L0ong thread here if you're interested, I'd say any oil is better than no oil, but carry a couple of litres of the right stuff with you, some people swear by 0/40 BTW

I use a fully synth 10/40 (Millers) £25 a gallon, which isn't too bad, all IMHO of course

[joospeed]

pepsi .. you're perfectly ok to use this oil in your car. tvr recommended 0/40 mobil for that engine anyway, people swap to thicker stuff to stem oil consumption, not normally a problem on 4 litre cars but is on 5 litre versions. 0/40 castrol will be fine.

[plipton]

joospeed said: pepsi .. you're perfectly ok to use this oil in your car. tvr recommended 0/40 mobil for that engine anyway, people swap to thicker stuff to stem oil consumption, not normally a problem on 4 litre cars but is on 5 litre versions. 0/40 castrol will be fine.

... Perhaps that's why the dealer used 10/60 for Pepsi's 5 litre Chimp. (my dealer used the same stuff in my Chimp 450 at its last service. Result - zero oil consumption!! )

Personally (and this is IMHO) I stick to what the dealer recommends as they know the car's requirements better than I do.



>> Edited by plipton on Monday 3rd February 13:51

[incorrigible]

joospeed said: pepsi .. you're perfectly ok to use this oil in your car. tvr recommended 0/40 mobil for that engine anyway, people swap to thicker stuff to stem oil consumption, not normally a problem on 4 litre cars but is on 5 litre versions. 0/40 castrol will be fine.

Know this is covering old ground, but didn't they reccomend the Mobil1 as they were sponsoring some Tiv race series, and they're now recommending a 5/40 or 10/40

I'm considering a groundnut oil myself, you get a much nicer engine smell after a long run