ive got a 95 wrx ive noticed recently that when pulling off or gentle reving i can hear a knocking sound but when moving or revving past 2000revs it stops or perhaps i just cant hear it! the engine was rebuilt about 10k ago but this was before i bought it, ive read alot of posts on here about piston slap on classics but the symptoms dont seem the same, any ideas guys??

also wanna do an oil change wondering what the best oil to use the car is used mainly for town driving and the occasional blip

 

piston slap is common it's usually when starting from cold, and goes when warm, if you are getting it all the time it can be a sign of big end wear, have you got an oil pressure gauge fitted? There are many opinions about oil but you won't go far wrong with Millers CFS 10/60

 

cheers, no oil pressure guage fitted how can i test that otherwise? what is the normal working oil pressure