Oil weight ?s

[zukinut]

As most of y'all know the truck drinks more oil than water.  I'm currently running valvoline 10w30.  Oil pressure is fine at higher rpms but down low it's about 25. A trick with 90s era land cruisers was to step up to 15w40 and it really did help with oil consumption and oil pressure.

Will it help with my 390 or is that to heavy of oil?

Thanks again for the help

Will

[Hemi Joel]

If the oil consumtion is due to worn rings, heavier oil will help considerably. Try 20w-50.  Too heavy? if it starts in the morning, it's not too heavy. True, thicker oil takes more power to pump, but it's not noticable on a street engine.

Some causes of oil consumption will not be helped much by heavy oil, such a s a bad PCV valve.

Good luck, Joel

[zukinut]

About the pcv valve, I've always heard that if air only flies thru it one way it's good.  Is that true.

Thanks again
Will

[machoneman]

No, it's not true. A PCV with a weak spring will stay open (partially or fully) when it shouldn't, allowing oil to get sucked in and burned.  One can check it with a screwdriver tip. Push on the engine side and see if it has some resistance (it will be light btw) and see if the check valve inside does close completely. Even if it seems o.k., clean it with carb cleaner or replace it.

Sounds like you might want to pop the valve covers and see if the end drains are clogged with crud.  That and checking to see if your valve seals are still intact or dried up and broken off.

I'd run straight 30W oil or even 40W if its burning oil a bunch. Heck, in one of my old cars long ago, I bought only Sears Roebuck's cheap 30W recycled oil since that Chevy burned and leaked more oil than the Exxon Valdez 

[zukinut]

Engine is super clean and umbrella seals are pliable.  I think I have a tired engine. The compression numbers are only 125 although they are all 125.

Will

[machoneman]

Even clean, an engine that maybe sat a long time or for a variety of reasons can develop stuck piston rings and/or oil scraper rings. Try a quart of this:

http://www.autobarn.net/ch100-qr.html?site=google_base&gclid=COPj05zI1LcCFfA7Mgodz0EASw

Rislone's original formula, even though they now have other ring specific/compression restoration products. Have not used the new stuff but the original stuff does work. Can't hurt for sure.

See Wolfman's post here. Haven't personally tried the MMO trick but many claim it works. 

http://www.saturnfans.com/forums/showthread.php?t=23676&highlight=mmo+soak

[jayb]

Engine is super clean and umbrella seals are pliable.  I think I have a tired engine. The compression numbers are only 125 although they are all 125.

Will

125 psi on the compression test is not necessarily bad.  That number will depend to a large extent on the compression ratio of the engine.  Do you know for sure what that is?  Since all of the numbers are the same, it is safe to assume that all the cylinders are acting the same.  The engine may not be tired, it just may be a low compression motor.

[zukinut]

Jay

I have no clue about the engine other than its a 2u crank 390 built in 69. There are no other numbers on the block except the date stamp.

I believe it may be a truck engine. It runs good and is super quiet and smooth. That's why I was afraid to put heavier oil in. I didnt want ti accidentally kill the oil pump.

Will

[zukinut]

And now idle oil pressure is 50psi. Is that ok?  U know these are Druid questions but I would hate to lose an oil pump.

Thanks again
Will

[Drew Pojedinec]

How is the PCV run?
I run the pcv hose to the carb spacer or back of carb and the oil fill cap hose to the intake where it has a filter.  In 1500miles I don't lose enough to bother topping off.  (I change oil every 1500-2000miles or whenever October rolls around)

my 390 runs 15w40 without issue, 40psi idle, 65psi wot
my 429 runs 20w40 and gets 60psi idle, 90psi WOT.  Considering just running 15w40 in both of them (I love the 5 quart containers)

[zukinut]

From pcv outlet on carb spacer to Oil fill cap. Jus like the factory intended. The pcv was suspect so I replaced it.

Mine blows blue out of both banks under heavy load or quick acceleration.  Ive been working it hard lately so it's been using its fair share.

How many quarts does a truck pan hold. None of my service manuals state how much it holds. 5 quarts brings it to full mark so I'm sure it's around 5.

Will

[ScotiaFE]

You can put 6 quarts in a stock car type oil pan no problem.
I think some truck pans are even bigger.
Next time you change oil pour 6 in the pan and remark the stick with a file mark.

You won't loose an oil pump, but you may twist the pump drive shaft. They are a hex stock that is
really quite weak. The ARP shaft is much more robust and at less than 20 bucks a good deal.

The blue smoke out of both banks/pipes?
Possible intake leak?
What are the plugs telling you?

[zukinut]

Don't you have to pull the pan to change the pump driveshaft. In a truck that means pulling the engine.

I can't get a picture of the plugs to turn out. #1&4 are light grey to white, the rest show a tannish brown. There are a couple that have deposits.

I have no vacuum leaks and no oil seeping anywhere.  I have noticed that if the breather and oil fill caps are off there is a fine mist of oil coming out. The baffles are all in place and the vc's are spotless clean.

Will

[ScotiaFE]

So your saying you have a 390 that was built in 69 and does not leak oil.

2U is pretty much the standard 390 crank from 66 to near the end, in cars and trucks.

An intake leak on an FE can be very subtle and cause a pretty good cloud out the pipes when you step on it.
You may only see a few points drop on a vaccume gauge.
The leak can also be in the crossover. Do you have a crossover intake?

[zukinut]

My 390 was rebuilt in 85. Well something was done because it's stamped 5-25-1985. On both heads.  I pulled the pan and regasketed it and did the same when I put the 4v intake on.  I don't see any oil around the ends. I used Toyota fipg and the cork. I have a crossover intake but I blocked it off with sheet metal the thickness of the gasket.

How would I go about finding a non visually detectable intake leak. It's a big ol nasty cloud of blue when ya stand on it.

Also why would plugs 1&5 be showing a lean or to hot of plug condition but the rest show an ok mixture? Could that be a sign of a leaky intake manifold?

Thanks again
Will

Thanks again
Will