Oil consumption-- 1qt/1000mi after break-in?

[Ganthrithor]

Another update: I changed the oil a few weeks ago, sent a sample, and just got the UOA results back from Blackstone. Here they are:



No coolant! Wootles!

[rice_classic]

Disappearing oil, if not leaking, might be from hard driving/corning and the PCV system.

This was absolutely the case with the s2000 engine. During cornering or sustained high rpms the oil splash pathway in the engine could be making its way into the PCV line and since the line is almost always under vacuum (or pressure from crankcase) any oil passing near the opening would get pulled in.

Just spaghetti at the wall at this point.

[Ganthrithor]

Originally Posted by rice_classic

Disappearing oil, if not leaking, might be from hard driving/corning and the PCV system.

This was absolutely the case with the s2000 engine. During cornering or sustained high rpms the oil splash pathway in the engine could be making its way into the PCV line and since the line is almost always under vacuum (or pressure from crankcase) any oil passing near the opening would get pulled in.

Just spaghetti at the wall at this point.

Yeah it seems to only burn through oil quickly when I drive it hard. If I rack up a lot of boring highway miles (heaven forbid), it quickly loses its appetite for oil. Maybe I should install a catch can?

[rice_classic]

Originally Posted by Ganthrithor

Yeah it seems to only burn through oil quickly when I drive it hard. If I rack up a lot of boring highway miles (heaven forbid), it quickly loses its appetite for oil. Maybe I should install a catch can?

Well, depending on design of the catch can it may be more for keeping crankcase oily-gasses from re-entering the intake air stream and being combusted. Some catch cans do recirculate but are designed so the air leaving the crankcase (dirty and oily air) gets cleaned up via the catch tank baffles and re-enters the intake stream more or less clean.

There's the possibility that neither will reduce your oil loss problem because instead of being consumed by the engine the oil you lose will just sit in the catch tank instead.

[Ganthrithor]

Originally Posted by rice_classic

Well, depending on design of the catch can it may be more for keeping crankcase oily-gasses from re-entering the intake air stream and being combusted. Some catch cans do recirculate but are designed so the air leaving the crankcase (dirty and oily air) gets cleaned up via the catch tank baffles and re-enters the intake stream more or less clean.

There's the possibility that neither will reduce your oil loss problem because instead of being consumed by the engine the oil you lose will just sit in the catch tank instead.

Oh, I know, I just thought if it's being recirculated maybe its better to keep it in a can instead of all over the valves. Then again, maybe it doesn't matter since we have port injection as well as DI.

[bakerr6]

Originally Posted by Ganthrithor

Oh, I know, I just thought if it's being recirculated maybe its better to keep it in a can instead of all over the valves. Then again, maybe it doesn't matter since we have port injection as well as DI.

go with the catch can. This will trap some of that oil. I wouldn't recommend putting it back into the engine, but if it''s going into the intake, this will be an easy way to keep it clean

[jonboy99]

Is a catch can likely to cause any warranty issues though?

[Ganthrithor]

Just another update-- new UOA is in:



Pretty sure my car has no mechanical issues at this point. I've been doing a lot more commuting miles (~75mph on the freeway in 6th) lately and my oil consumption has been pretty negligible: haven't topped off at all since my last change (over a thousand miles ago) and the level is still ~2/3s of the way up the usable area on the dipstick.

[asnoir]

Have you got an oil cooler? Your oil reach high temperatures with wot. Use a sandwich plate oil cooler as on forester. There is the cusco oil cooler too !
http://www.ft86club.com/forums/showthread.php?t=33799

[CoupedUpSubie]

I was just thinking about this. My job has me working with large diesel engines, 1,000 hp and up. It is generally normal for the first bit of oil to be burned off after an oil change. As long as there are no leaks the oil generally stays at one level, if you add oil it will just burn it off. These are engines with 40+ gallons of oil. Each engine has its own happy spot for the oil level.

For those with problems I would as if they are constantly topping off their oil because its down by 1/4 of a quart.

[Koa]

Originally Posted by CoupedUpSubie

I was just thinking about this. My job has me working with large diesel engines, 1,000 hp and up. It is generally normal for the first bit of oil to be burned off after an oil change. As long as there are no leaks the oil generally stays at one level, if you add oil it will just burn it off. These are engines with 40+ gallons of oil. Each engine has its own happy spot for the oil level.

For those with problems I would as if they are constantly topping off their oil because its down by 1/4 of a quart.

I respect your experience first off- one question: what do those diesel systems have to do with ours in terms of oiling characteristics that make this a solid connection?

[CoupedUpSubie]

Originally Posted by Koa

I respect your experience first off- one question: what do those diesel systems have to do with ours in terms of oiling characteristics that make this a solid connection?

The majority of engines use the typical design of pistons on connecting rods on a crankshaft. These engines all use engine oil for the same things:

Lubricate bearings, valve train, help create a seal and lubricate piston rings, aid in cooling.

The biggest difference is really just oil weight.

[Koa]

Originally Posted by CoupedUpSubie

The majority of engines use the typical design of pistons on connecting rods on a crankshaft. These engines all use engine oil for the same things:

Lubricate bearings, valve train, help create a seal and lubricate piston rings, aid in cooling.

The biggest difference is really just oil weight.

the combustion cycle is the same yes.. so no real discrepencies about the compression/charge differences betwen petrol and diesel engines and oil usage? The only diesel I've ever owned was a little tdi that I kept bone stock, so I haven't ever delved into the issue much.

As far as oil differences go, I do know that typically additives too should be taken into consideration as diesels create significantly more soot/byproduct ay? Would these have any impact between differences in the two?

you can tell I don't interact with many diesel mechanics baha. Sorry if the questions seem 'duh' or elementary, or able to be googled. I am in full lazy wednesday mode.

[CoupedUpSubie]

Originally Posted by Koa

the combustion cycle is the same yes.. so no real discrepencies about the compression/charge differences betwen petrol and diesel engines and oil usage? The only diesel I've ever owned was a little tdi that I kept bone stock, so I haven't ever delved into the issue much.

As far as oil differences go, I do know that typically additives too should be taken into consideration as diesels create significantly more soot/byproduct ay? Would these have any impact between differences in the two?

you can tell I don't interact with many diesel mechanics baha. Sorry if the questions seem 'duh' or elementary, or able to be googled. I am in full lazy wednesday mode.

I just got off the boat I work on, 28 day hitch, so I have the lazy Wednesday feeling also.

The big differences in diesels and petrol engines are combustion source, fuel injection, higher compression(14-22:1).

You are correct on the oil additives. These are mostly to counteract any fuel dilution or soot that gets picked up in the oil.

My theory on the oil consumption is basically just a theory. Some people seem to have actual issues that shouldn't happen. In a 6 quart engine I'd have no issues with a .5 quart drop after an oil change as long as it doesn't get lower.