After the engine rebuild I put Castrol 10W40 semi synthetic oil in it. While the car is running fine, it still sound tappety, and gets quite harsh at 2500RPM+. I've asked on some Facebook groups and somebody's recommended using 20/50 mineral or semi instead. Anybody used this in a CVH before?
Cheers.

 

I only use mineral oil for running in, not semi, its too good IMHO

 

i used 20w60 in my 720 hp rb26 engine and it had been useing it for over 10k miles without issues, if will help maintain pressure if youve got a high clearance race engine.

tbh though it shouldnt need thick oil to quieten the tappets down, is the motor holding good oil pressure ?

 

Castrol GTX used to be 20/50 and was one of the main reasons CVHs got the 'black death' back in the day..

 

A 20w oil will only maintain it's viscosity down to about -8 so may not be very good in the winter in the uk lol

 

Ah yes I've heard of that. Didn't realise it was that grade of oil that caused it. Thanks, you may have saved me a lot of upset lol.

 

i have had my astra dti work van from 4 years old and it had done 40k miles when i got it, its now done 183000 miles and the engine and turbo is still untouched, it has been run on 20w40 mineral oil for all those miles at about 7000 miles service intervals.

it has been used all year round for 10 years in it, and all our machines run on it to all year round.
my 720 hp rb26 had been running 20w60 for at least 6 years and over 10k miles and still going strong.

 

All good then but even so it dose not have a very low temp rating after all the number before the w is it's winter rating the other number is the viscosity.
-8 ish is largely a lot colder than the uk gets but I'd have to say a 10w to me just seems safer

 

Go for a 15w50

 

+1

the engine will run many miles with a 20W-60, no doubt, but the fewest will open the engine to see the mess and how much oil will it burn after some usage? The engine won't explode but the engine wear is huge esp. in winter..... Well, the engine runs don't mean the oil is good, the question is HOW the engine runs and how it looks inside. You can't see it from outside.

Could imagine that the tappets will make noises for 20 sec. on a strong winter day at -20 with a 20W-60