Wondering if I should switch to a heavier weight oil. Engine seems to run fine, but will smoke a little when engine is fully warmed up. I suspect there is an underlying issue with an oil ring(s) possibly, since I have changed out all the intake and exhaust valve seals and intake gasket a year ago. Low mileage on the engine since it's only a weekend/nice day car. 1983 Camaro with a 408 Dart Little M small block, AFR 195 heads, canton road race oil pan with scrapers and windage tray. I installed a oil catch can inline with the PCV valve and it made no difference. - Has a Magnuson MP 122 blower on top with a FItech 1200 plus power adder throttle body injection.

- I currently run 10W-40 synthetic oil, and am considering running a 15W oil. Does running a slightly thicker oil generally help or hurt things? I've seen many performance engine builders recommend running a thicker oil in other engines, so wondering if I should be doing the same. Since my engine has a roots blower it never sees rpm's above 5500 really.

 

Increasing oil weight has more to do with maintaining a working film of protection in demanding environments (high rpm, high temperature) than it does with decreasing consumption. You may experience reduced consumption with a thicker oil, but it probably won't be substantial enough to notice. Have you done a compression / leakdown test?

 

Yes I have. Twice. Both seemed good. No big deviation (>10%) between cylinders. Then I thought maybe it was sucking a little oil from the valve cover via the PCV valve and sending it to the throttle body port, so I installed a catch can inline. No oil residue inside the hose going to the TB port so I kinda ruled that out. Then I figured maybe the intake or exhaust valve seals might be leaking through even though the heads are pretty much brand new.....nothing changed. Then changed the intake gasket and it did nothing. I did noticed a little oil that was pooled up in the intake after I removed the blower though.....like a light sheen of oil just in the rear of it, which is why I installed the oil catch can....I don't know how it's getting there.

 

Possibly a leaking intake manifold gasket or from the center 4 bolts. Did you thread seal the center 4 bolts? Without thread seal those 4 bolts will leak substantially onto the outside of the manifold on a standard intake much less into intake manifold vacuum on your plenum.

 

Yeah, I've seen that in the past on other engines. I used thread sealer on all the bolts and still end up with oil.

EDIT: I was hoping someone might have any other ideas of why I'm burning oil....it's not much but enough to turn the spark plugs a blackish color. The only thing I can come up with is either an issue with some oil rings or with this intake. I know it sounds far-fetched, but I'm grasping at straws here...next time I remove the intake I'll pour water inside and see if any seeps to the other side underside of the intake - which would indicate a porous casting that could allow oil to leak in?!?

-If I find nothing, I will really have no choice but to pull the entire engine and have it re-honed and re-ringed. I hate to do it since this engine/heads are essentially new and has maybe 4-5K on it. I'll most likely have the heads rebuilt while it's apart also. I was asking about running a thicker oil with the thought it's maybe an oil control issue.

Open to any other ideas....