Hey guys,

I have a built k20a2 with looser tolerances that makes the vtc rattle on cold starts with 20w-50 vr1 in it. I ended up going to 15w-50 Mobil one but it still made the noise. Oil pressure on warm idle never drops below 20 psi. I then went to Rotella T6 5w-40 which completely stopped the noise, but now my oil pressure drops between 12-14 psi on warm idle getting off the highway and my oil light flickers while parking. Is it possible that the engine requires a 50 weight or more likely that my oil pump or main bearings are shot? The oil light does stay on for 2 seconds or so on cold starts as well. I’d appreciate any input.

Thanks!

 

risky to be driving on low oil pressure.
I would drop the pan to inspect oil pick up and check oil pump.
shouldnt be bandaiding the issue by changing oil viscosity

 

I'm a D-series guy, so take my advice for what it's worth. I'm running an OEM unmodified pump on my car, and I believe my rod and crank bearing clearances were all 0.0016" - 0.0018". My pan is not dented, I've had it off since the initial build, and the pickup is fine. The pump was new when the engine was built 2 years ago and I've even had a different oil pump (Melling) on there for a bit. I've experimented around with oil viscosities also, and finally just landed on 10W-30 VR1. In the dead heat of summer, fully warmed at a stoplight, my oil pressure can be as low as ~8-9 psi...my idle speed is set to 1,000 RPM. It used to freak me out, but it seems like it's enough pressure and it has no problem making oil pressure at higher RPMs.

 

Maybe I’m worried about nothing then lol. I drive the car every day so I’d rather not drop the pan unless I see something scary. Does freak me out that the factory sensor faintly blinked a few times though... I changed it out again to 20w50 vr1 and it never dropped below 22 psi coming off the highway, around 70 psi at 3k. Guess it just likes the thick stuff. It does have acl race bearings set loose but I would think I should still be able to run a 40 weight. The shortblock was built by a well known machine shop but I did all the rest of the work, all upgraded timing and all kinds of stuff.. got a super damper too. The pump is factory, didn’t do anything to it unfortunately but my rev limiter is 8650 for now.

 

Is it possible then that my bearing clearances are too loose if I can’t run a 40 weight with decent pressure? Because it seems to me if the pressure stays where it should be with a 50 weight that the pump is fine.