Hi all, I have a 2002 Z06 with a 383 stroker, with forged internals, mahle pistons, etc, but that's all the info I was given on engine. Its a dedicated track car and I do HPDE's with it so I have 3 catch cans on it. lol.
It runs strong but has a ton of blowby, which is common, and if run it hard will push oil dipstick out.

My question is can I use a thicker oil to help reduce blowby? Like 15w50? or similar
I currently run Driven DT40 5w40 oil.

 

Oh I might add, this car was a Mallett Hammer edition, with the engine built way back in 2002, Im pretty sure.

 

If it is pushing oil out the dipstick the issue isn't the oil, it is crankcase pressure. Solve that problem first.

 

Depending on bearing clearance you could use a thicker oil. A friend of mine who is an old timer has a truck with a 5.3 and has been running Casteol 20W50 since the day he bought it new. He said his LS motor would always have lifters ticking until the engine warmed up and I told him to start running 10W30 because that is what's reccomended for these factory engines. Well he started running 30W and the oil pressure is lower than what he's used to seeing but the lifters aren't ticking when he starts it up anymore. What size are the lines coming off your valve covers? Seems like you still have excessive crankcase pressure if your pushing the dipstick under heavy loads.

 

I was at the track a few years back. A guy showed up with maroon Mallet Corvette. The cam duration was in the 240's from what I remember and it would barely idle. He said the engine back in the early 2000's was 30K.

 

If your catch cans all have wimpy stock 3/8" lines then that's your problem. You need 1 or more 3/4" lines to let that crankcase breathe.

 

Agree with Supercharged above, you need bigger lines. The valley to intake (dirty side) takes a lot of work to increase but if you weld a AN -10 bung to each valve cover, run that to the intake tube behind the maf. Flow will reverse anyways so that will allow the excess pressure out. Or get a pressure relief valve in the catch can.

 

If you go this route, don't be like the PO of my car and rip the baffles out too. Leave the baffles in place or else your consumption will go up. Someone makes a baffle that screws into the oil cap that looks like a slick way to make it breathe. I think it's more important to increase its ability to exhale than to inhale.

 

A more viscous oil will likely have no effect on blow-by. In some cases, it can increase it.

Driven DT40 5W-40 is a good oil for your application and use. I don't think there's much you could do on the oil end to help with this. A lesser, more volatile oil would make the situation with the catch cans worse regardless of the viscosity. Driven DT40 5W-40 is less volatile than Mobil 1 15W-50, for example.

 

You could consider running more than one PCV valve/system.

 

get a vacuum pump.