Engine Oil Consumption

[fun331]

My 89 uses a bit of oil. I run the stock valve covers with a good set of roller rockers and had to clearance the oil fill baffle with a grinder years ago. It uses about a quart between oil changes, could that be the cause? I used to have an Edelbrock Performer EFI intake on her and when I took the side of the plenum off the first four runners were oil darkened. My heads have about 50 000 miles on them but were built in a good shop with quality parts. No blue smoke in exhaust, no oil smell. My short block is a CHP pro street with the low comp pistons but it's only got 10000 miles on it. The old engine had the same issue. PCV valve rattles freely. Any chance replacing that baffle would fix my problem?

 

[General karthief]

I would check the screen at the bottom of the hole where the pcv drops in. Pull the pcv, the rubber grommet come out the you can get to the screen. Some guys take the upper intake off to get at it a little easier, some just fight it with a long L shaped pic. It may not be there and why you have a consumption issue, which a quart per oil change is not bad although mine never uses a drop.

 

[JD1964]

I've heard that the wrong thermostat can cause minor oil consumption. If an engine is put together with clearances that are stock, and the stock thermostat is a 192, then that is the design temp for heat expansion and proper sealing of the rings. Run a 180 thermostat and proper ring sealing may not happen.

 

[fun331]

I'll check the screen, thanks.
The ring clearances may be an issue I didn't consider. I am running a power adder ring package without the power adder. It's been years but I'm pretty sure it's a 180 degree fail safe thermostat in her. It doesn't run much over 180 unless you're in traffic so it may have failed and is open.
I pulled the vacuum line that goes from the oil fill neck to the throttle body ( and plugged the ports) just after I posted. Not sure if that was smart or not. I was trying to keep the vacuum from pulling oil past the baffle. I've been cruising around without that line since August. Bad idea or not?

 

[JD1964]

That line is where the Pcv system gets its supply air. Removing and plugging it can cause other problems like 1) preventing the pcv system from working properly, 2) causing the vacuum draw from the pcv system to result in gasket failure (any gasket that plays a role in sealing the crankcase). 3) if MAF car, not allowing the MAF to measure air being ingested by pcv system.

Long story short...bad idea

 

[fun331]

Thanks for the advice, I replaced the vacuum line.

I would check the screen at the bottom of the hole where the pcv drops in. Pull the pcv, the rubber grommet come out the you can get to the screen. Some guys take the upper intake off to get at it a little easier, some just fight it with a long L shaped pic. It may not be there and why you have a consumption issue, which a quart per oil change is not bad although mine never uses a drop.

I run an Edelbrock RPM II intake and there's a screen in the bottom of the grommet that the PCV fits into. My grommet is siliconed into the intake though so I didn't rip it out .Is there supposed to be another one?
Maybe it is temperature related. My car doesn't run very hot, usually around 160-170.

 

[JD1964]

At that low temperature the computer may not even get into closed loop. It needs at least 180 or better for closed loop where the computer default settings change and give control to the O2's.

 

[@408Stroker]

I'll check the screen, thanks.
The ring clearances may be an issue I didn't consider. I am running a power adder ring package without the power adder. It's been years but I'm pretty sure it's a 180 degree fail safe thermostat in her. It doesn't run much over 180 unless you're in traffic so it may have failed and is open.
I pulled the vacuum line that goes from the oil fill neck to the throttle body ( and plugged the ports) just after I posted. Not sure if that was smart or not. I was trying to keep the vacuum from pulling oil past the baffle. I've been cruising around without that line since August. Bad idea or not?

That vacuum lune has to be there to complete the pcv circuit. Remove it and under high vacuum situatios you will pull unmetered air past your main seals. BAD IDEA.

 

[fun331]

Thanks for all the info folks. Any preferences on a thermostat? 180 or 192? If my old memory is right, doesn't Ford recommend a 192?

 

[JD1964]

The factory thermostat is a 192. If your rings are gapped for a boosted application, that means the end gap is larger. So, a hotter running temp would close that up some. I can't see how it would hurt anything to give the 192 a try. I also recommend full synthetic oil if you're not already running it. I run Mobil 1 in all my cars. 10w 30 full synthetic in my Mustangs. Other weights in my other cars.

 

[fun331]

Thanks again for the great info. I like the 10W30 best myself. I found the lighter grades like 5W20 make the oil pressure low at idle when she was hot. Always had full synthetic since I spun a bearing at the strip years ago. I also use Mobil 1 mostly but I have Lucas in her now and I may try Royal Purple. If you're changing it yourself and saving the cost of the labor why not put the best oil in.