E30 Zone

I have a m20 325 turbo I think the turbo may be on its way out sometimes get a puff off smoke what's the best replacement as the one fitted is a Chinese cheapo I think it might have a t4 on it or t3/t4 I'm no expert just looking for advice on a swap

Also when servicing the engine which oils should I use ? Also the oil feeds to the turbo etc how do I know if there flowing around the right amount of oil to keep it cool ? Any help would be good

What size turbo is it? You will need to replace it with a similar sized one or have it reconditioned. If it's a Chinese knock off look for something from a reputable manufacturer.

What size are the pipes going to and from the turbo? And is it a top mounted?

a good 10w40 syn would be good the oil doesnt keep a turbo cool its just for lubricating the bearings

a t4 or t3 doesnt mean nothing thats just the flange size you need to know the ar of each housing and the inducer and exducer sizes you could take the housings of and measure each side would be a better indication of what you have
what sort of revs does it start building boost ?

if its early its prob a .63 ar turbine or late revs could be up to a .82 or above
the comp housing i bet is prob a .70 ar most of them chinese ones are

if the flange is quite big and square its a t4 if its like a rectangle its a t3 but you still need to know the diameters of the impellers

Cheers for the feed back , I haven't had time to get the measurement of the turbo but the turbo does kick in really late theres also quiet abit of lag before it kicks in again when you change gear I'm guessing turbo is to big ? . I have been looking on eBay at garret turbo for saabs but I'm getting lost with all the numbers and sizes they say. I'm wanting to run 300 bhp on a decent turbo . I will try get a pic up tomo .