Outer Limits 4x4 Board

I've got a HZJ80 cruiser with aftermarket turbo. Previous owner rebuilt the motor 20k or so ago and said he always used Penrite HPR 20W50.

Have noticed in the colder weather the motor has a bit of a knock/rattle for a minute or two til it is warmed up. Once warm, motor is fine. I am in Brisbane so it doesn't get too cold overnight.

Is this likely to be caused by oil pump not able to deliver thick cold oil quickly at startup, or are there othere likely causes for this type of noise when the motor is cold?

I am off to the cape in mid June so am wondering should I continue with the 20W50 at next oil change (due now) or go for a thinner oil over winter and/or all the time

cheers
CK

I think the factory turbo models specify a 15/50 oil... so there wouldnt be any harm in running the penrite 15/50 in yours, it should improve your knock at cold start up.