Oil Level/Comsumption

[mike100]

Thinking about it, I just changed my oil a couple of days ago. Almost exactly at 5000 miles, and 12-1/2 months between. I believe I added 3 qts in the span of the year, with much of the 3rd qt still remaining, so I'd say 2.x qts in 5k miles.

Seems very LT5-like, especially since I only drive this car when I want to play, less so commuting or whatever. The last time I drove 400 miles to AZ, i did it real slow to save gas and avoid tickets...no loss of oil noticed, but i flogged it hard on the return trip and used 1/2 qt. It's mostly pcv blowby as far as I can tell.

I may let it get a qt low and run like that for awhile to see if the consumption rate slows or stay constant to see if my windage theory makes any sense.

[Paul Workman]

Originally Posted by mike100

Thinking about it, I just changed my oil a couple of days ago. Almost exactly at 5000 miles, and 12-1/2 months between. I believe I added 3 qts in the span of the year, with much of the 3rd qt still remaining, so I'd say 2.x qts in 5k miles.

Seems very LT5-like, especially since I only drive this car when I want to play, less so commuting or whatever. The last time I drove 400 miles to AZ, i did it real slow to save gas and avoid tickets...no loss of oil noticed, but i flogged it hard on the return trip and used 1/2 qt. It's mostly pcv blowby as far as I can tell.

I may let it get a qt low and run like that for awhile to see if the consumption rate slows or stay constant to see if my windage theory makes any sense.

Seems we've stumbled on some new ground in this thread!

P.

[Hib Halverson]

Originally Posted by efnfast

Hib, do you go 8k between changes? I know oil is important, but it seems many people change it far too often. Wasn't it Jiffy lube that started the 3000 mile oil change? Subject of a new thread?

I go 15,000 miles or every two years on oil changes, but....

1) I use Red Line 10W30, not Mobil 1. That allows extended drain interval
2) I change the filter every 5000 miles.

I've been doing this since I got the car.

The 3000 mile oil change was a valid choice 50 years ago, but not today. It's wasteful, inefficient and environmentally irresponsible.

As for oil use, the 90s were the only LT5s with no exhaust valve stem seals. GM found that, in practice, stem seals were needed on the exhausts and began using them in 1991 engines.

It was said earlier that the OE design of the LT5 with open deck cylinder case was prone to oil consumption problems.

I'm not sure that's true of stock or near stock engines and, given proper cylinder wall thickness, proper cylinder wall finishing and proper liner installation, I don't think it's true of modified engines.

I'd sure be interested to see any documentation and testing Paul Workman has to support his statement.

[scottfab]

Originally Posted by GOLDCYLON

Yep Concur the MY 90 had no seals for the exhaust valves. That started MY 91. However, before I replaced my motor it always burned through the first quart real fast. Another question if I may does anybody see a lot of black soot/carbonation on their rear fasica from there exhaust like I used too? GC

Yup, I see the soot. If I make the mistake of starting before opening the garage door I get two big black spots. Not exactly fun to clean.
Otherwise I get the two spots on the driveway just outside the door.

[Blue Flame Restorations]

In reference to getting a more accurate oil level reading. I like to check my oil before I fire up the car in the morning, when checking. It's trivial, but it does make sense to use this method when possible.

[GOFAST]

Thanks for all the great feedback/information. BTW, I replaced my PCV valves about 5000 miles ago. I have also found that the quantity of oil required to move from "add" to "full" on the dipstick is less than 1 quart (probably 2/3 of a quart).

Thanks again,

Gofast

[scottfab]

Well I topped off my oil early this morning and just checked it.
It does go above the fill mark by about 1/8th in.

BTW I go through a lot less oil if I keep it at the add mark and not the fill mark.

[gbrtng]

Originally Posted by Hib Halverson

An engine using a qt. every 1500-1800 street miles is likely in need of some service...perhaps valve stem seals. That seems like a lot of oil use for an LT5 unless it's very high mileage or maybe using a 5W30 or 5W20.

I've been using 10W-30 - both conventional and synthetic - since 8k miles
when I bought the car in 1995. 1500 miles on a quart is fine with me and well within warranty limits for a new vehicle per GM's criteria. And this is a 91 with the seals on both intake and exhaust ... The burn rate has not changed in 40k miles.

[Paul Workman]

Originally Posted by scottfab

Well I topped off my oil early this morning and just checked it.
It does go above the fill mark by about 1/8th in.

BTW I go through a lot less oil if I keep it at the add mark and not the fill mark.

Well, this news may aly my concern about oil consumption - above the add mark. Next time I have a long trip in store, maybe I can get a chance to do some experimenting/documenting.

Interesting topic.

P.

[sammy]

Originally Posted by mike100

I can concur that that doesn't sound excessive, although I would admit that I was worried about it when i first got the car. The only observation i can share is that the "top" quart burns quickly, but after it is running a quart low, the windage losses seem to be less.

i find that the same happens with me on the top QT.what is also interesting is when i tried changing dipsticks between my 90 and 92 the oil level didnt read the same . the 90 stk in the 92 read full when the 92 read add. are they different ?????