Oil consumption after rebuild

[Alan43]

Engine guys please help! I had my engine rebuilt on my 91 GW, 360, recently by a local engine rebuilder with a good track record. It's been 1200 miles since the rebuild. So far, I've been using a quart of oil consistently every 300 miles. Four quarts added so far. I took it back to the shop for a look, and the shop checked the plugs (not fouled) and there are no external leaks. It's running great otherwise, no more pinging, runs on regular now not premium, and is full of power. The oil was changed at 500 miles and I'm using 10W30. The builder says I need to wait up to 3000-4000 miles before the rings seat, and I should just watch and keep adding oil until then. No need for concern. Does this sound right? I'm not an mechanic, but I never had a new car go through oil like this. Do I have a problem? Thanks!

[Mikel]

Some fuel consumption is normal. I would say just wait...

[woodybeone]

That is correct. I would change the oil/filter at 1500 and again at 3000 then track it from there. Did he prelube/pressurize the motor before starting?

[River Beast]

oil comsumption on a new motor is normal... how much... not sure... the rings need to seat and everything is fresh...

now.... one mistake some people make is using synthetic oil in a new motor... bad idea...I have heard from more than enough reliable sources that regular motor oil is what is needed to 'break in' a new motor... synthetic blends will not allow the rings to seat (no persnal experience.. I dont use synthetic)... thus create an oil comsumption problem right off the bat... FYI

[Chevelleguy]

To speed up the ring seating process, you can block the radiator and get the engine temp to about 230-240 deg. then shut the truck off and let it cool for 30 min. then repeat 2-3 times. This should get the rings seated. Late modle cars cooling fans don't even come on till 230 so don't be afraid of damaging your new motor.

[oldyellowwagoneer]

Find out if they used a valley pan type intake gasket and reinstalled the shield on the bottom of the manifold. Without either of these you will use oil and not foul plugs. You need both.Dennis

[Chero77]

Sounds like something is wrong to me. My rebuild had no noticable change in oil level in its first 3000 miles. Try and find out if your rebuilder used chrome rings as they are notorious for not sealing. Still, even if he did, a quart every 300 miles is way to much.

[mojolounge]

Chero77 has a good point,as well let the engine warm up real good before you drive it. The break in process of a new/rebuilt engine is vital to the overall longevity of the engine. But that oil has to be going somewhere!

[Alan43]

Thanks guys! I'll wait a while and see. The rebuilder said a little oil is getting by the rings on each stroke and will keep using oil for a while, and that it varies with each engine.

1) Woodybeone: Don't know if they prelubed the engine before staring. But, I think they are compentent because the local Jeep Dealer mechanic said this is the builder he would have his engine done at.

2)River Beast: I'm not using synthetic oil, in fact the rebuilder made a point of telling me not to use it.

3) Oldyellowwagoneer: I didn't mention it in my post, but the rebuilder (he seems to really know AMC 360's) mentioned this area as a oil loss point. Said all was okay.

4) Chero77: Don't know if they used chrome rings. If it keeps up I'll ask. Thanks!

[Don S]

..
Alan43;
... In the late 1950s I was a servicewriter, line mechanic, parts manager, trouble shooter and general flunky for AMC. The AMC engines were having an oil consumption problem. The cause was changing the factory break-in oil at 500 miles and installing high detergent oil.

... Using about twenty test cars, we ran the AMC factory brake in oil for 500 miles. Then installed non-detergent oil that was successful in seating the rings (in those days). The non-detergent oil was dumped when the car reached 1500 to 2000 miles and replaced by high detergent oil.
... These engines would get about 2500 miles per quart but we normally changed oil at 1000-1500 mile intervals. I remember doing this to AMC engines in 1959. If we put detergent oil in at 500 miles the engines would burn like a quart every 500 miles.

have a good one.. ;) .. Don S..