Oil Level/Comsumption

[GOFAST]

I have a '95 with about 12k miles. I purchased the car about one year ago and have found it difficult to get a consistent oil level reading on the dipstick. My last oil change was about 3k miles ago (Mobil 1 XP 10W30), and I added about 8 2/3 Quarts which read slightly below the full mark on the dipstick. Since the change I have added the remaining 1/3 Quart (9 total), it now reads in the middle between add and full.

The engine has either started to burn oil or I just never got it full from the last change. I would appreciate your input/experience.

Thanks.

[PhillipsLT5]

Wait overnight or 24 hr to check
Let the same amount of time to pass with each check for consistency
These cars will normally use some oil especially with spirited driving

http://www.zr1specialist.com/HAT%20Web/articles/Modern%20Motor%20Oil%20and%20the%20LT5%20Engine.pd f

http://www.zr1specialist.com/HAT%20Web/articles/Oil%20Filter%20Recommendation%20Update%202011.pdf

[gbrtng]

My 91 uses about a quart in 1500-1800 miles on the road. On the track about a quart in 300 miles. Typical from what I have heard.

[mike100]

My 91 uses about a quart in 1500-1800 miles on the road. On the track about a quart in 300 miles. Typical from what I have heard.

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.

[Hib Halverson]

I don't think you need to wait a day but you do need to wait several hours to get an accurate read of oil level from the dip stick.

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.

With my LT5, I've never experienced the "top quart" burning quickly.



My 95, with about 60,000 miles on the motor, uses a quarte in about 8000 miles.

[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?

[tomtom72]

I thought that the 405 hp motors got exh & Int valve stem oil seals? I'm almost positive the 375 hp motors are missing one or both, I think it's only the exh seal they left out?

Anyway, GOFAST how are your PCV valves? I change mine every year as part of my "get ready" for the season. I have noticed that they don't make that clear metallic clinking sound after a season's worth of use, for me somewhere between 6k to 8k miles. As I get towards season's end my oil use goes up or becomes accelerated if you'll allow me that phrase. I can't find the oil on the plugs. Anyway, my point is my LT5's use seems directly related to the health of the PCV valves...or at least that's JMHO thru my own observation. Oh yea, pounding on Her just seems to speed up oil loss no matter when I do it. One of the development issues LOTUS had, ccv blow by ( my words, not LOTUS ), as there is no place for the internal wind with oil in it to slow down enough for the oil to coalesce and fall out of the air stream. Or at least that's what I think they, LOTUS, was saying. I would think that if that is true, then how clean the PCV valves remain over their time in service would be very important to oil loss?

As for checking the oil level. I use my car only on weekends and that's when I check my oil as part of my pre-start up check list. I always get consistent readings from the dipstick. If you think about all the places in our heads that oil can hide I can easily see 4 or 5 hrs should pass before all the oil gets back to the pan. Okay maybe a bit less?

These are just my observations with how my engine behaves in this regard.

:cheers:
Tom

[Paul Workman]

I thought that the 405 hp motors got exh & Int valve stem oil seals? I'm almost positive the 375 hp motors are missing one or both, I think it's only the exh seal they left out?

Anyway, GOFAST how are your PCV valves? I change mine every year as part of my "get ready" for the season. I have noticed that they don't make that clear metallic clinking sound after a season's worth of use, for me somewhere between 6k to 8k miles. As I get towards season's end my oil use goes up or becomes accelerated if you'll allow me that phrase. I can't find the oil on the plugs. Anyway, my point is my LT5's use seems directly related to the health of the PCV valves...or at least that's JMHO thru my own observation. Oh yea, pounding on Her just seems to speed up oil loss no matter when I do it. One of the development issues LOTUS had, ccv blow by ( my words, not LOTUS ), as there is no place for the internal wind with oil in it to slow down enough for the oil to coalesce and fall out of the air stream. Or at least that's what I think they, LOTUS, was saying. I would think that if that is true, then how clean the PCV valves remain over their time in service would be very important to oil loss?

As for checking the oil level. I use my car only on weekends and that's when I check my oil as part of my pre-start up check list. I always get consistent readings from the dipstick. If you think about all the places in our heads that oil can hide I can easily see 4 or 5 hrs should pass before all the oil gets back to the pan. Okay maybe a bit less?

These are just my observations with how my engine behaves in this regard.

:cheers:
Tom

Hi Tom,

Your're correct, far as the 90s go. They were sans seals on the exhaust valves - per Lotus Engineering felt those valves needed extra lubrication (ref: Heart of the Beast?). I've also read where the particluar open deck architecture employed in the LT5 is prone to some oil consuption, as a result of the top of the sleeves anchored to the head via friction. Sleeve lenght uniformity is absolutely critical to oil consumption, and tollerances being tollerances, and vibrations and stress being what it is (read: sleeve instability), sleeve stability contributes to oil consumption.

http://i185.photobucket.com/albums/x220/6PPC_bucket/stockblocksleeves.jpg

Marc's caging the sleeves in his BIG inch builds seems to be addressing at least some of the oil consumption (have to ask 'im or Frank U) by stabilizing the sleeves (reducing the dependance on friction against the head for stability). I've not heard yet if AES' closed deck design is effective in reducing oil consumption, but clearly that design stabilizes the sleeves as well.

http://i185.photobucket.com/albums/x220/6PPC_bucket/Closeddeck7_zps9e2edf4b.jpg

(Maybe someone with REAL expertise could chime in? :o)

Comments about "first quart" consumption was news to me. And too can you or anyone tell me if the hashed segment on the dip stick represents a quart or is it something less? I put in a quart when the level was just below the hash, and checked it the next day. The level now as above the hash (full) line by an equal amount....WTF? I'm wondering if the seal on the dipstick caught on the edge of the tube and maybe didn't allow a proper sounding of the oil level. Have you (or anyone else) ever noticed that??

From the way I drive (spirited ... Hey, living in the country has its advantages!;)), my consuption has always been a quart and a little more between 5000 mile changes. After getting hot a couple times, and having a coolant disaster once, I'm monitoring it closely for a while to see zackly what it is now. (I have seals on all valves now).

Gotta run!

P.

[scottfab]

...snip....

Comments about "first quart" consumption was news to me. And too can you or anyone tell me if the hashed segment on the dip stick represents a quart or is it something less? I put in a quart when the level was just below the hash, and checked it the next day. The level now as above the hash (full) line by an equal amount....WTF? I'm wondering if the seal on the dipstick caught on the edge of the tube and maybe didn't allow a proper sounding of the oil level. Have you (or anyone else) ever noticed that??
...snip..

P.

I have an opportunity to verify this right now. Mine is right at the bottom mark now. I'll add a qt and check it in 8 hrs or so.

[GOLDCYLON]

Hi Tom,

Your're correct, far as the 90s go. They were sans seals on the exhaust valves - per Lotus Engineering felt those valves needed extra lubrication (ref: Heart of the Beast?).
P.


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

[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]

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]

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]

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]

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]

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]

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 ?????

[GOLDCYLON]

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 ?????


No they should not be

[sammy]

.i then just cant figure out what is going on . i havent done anything to either dipstk or tube .

[Mahogaraunch]

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.

To revive and old thread, after 5 months of not running at all, I started my '90 today, and let it idle for about 30 min. I noticed only when reversing back into the garage, a bit of blue oil smoke was coming from the exhaust. The garage had a burnt oil smell to it. I cant remember if the same thing happened last year or not. In any event, the car has 13,000km on it, and i probably put on around 900km last season. I checked the oil, looked clean, with a tiny bit of soot on the dip.

Not sure if the exhaust valve stem seal is the cause of the blue smoke or what?

What are your thoughts?

[GOLDCYLON]

To revive and old thread, after 5 months of not running at all, I started my '90 today, and let it idle for about 30 min. I noticed only when reversing back into the garage, a bit of blue oil smoke was coming from the exhaust. The garage had a burnt oil smell to it. I cant remember if the same thing happened last year or not. In any event, the car has 13,000km on it, and i probably put on around 900km last season. I checked the oil, looked clean, with a tiny bit of soot on the dip.

Not sure if the exhaust valve stem seal is the cause of the blue smoke or what?

What are your thoughts?

Idle fuel Injectors. GC

[GOLDCYLON]

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.

Yep I can relate to that happened. Pre engine exchange that was a daily occurance

[Mahogaraunch]

Idle fuel Injectors. GC

I'm not mechanically inclined so could you explain that to me? I did have all 16 injectors replaced 2 years ago.

[GOLDCYLON]

I'm not mechanically inclined so could you explain that to me? I did have all 16 injectors replaced 2 years ago.

Sure. You stated you haven't driven much. I am suggesting the blue smoke could be a combination of no valve seals and/or your fuel injectors may have built up deposits that need to burn off with a little spirited driving

[Mahogaraunch]

Got it now. Thanks. I'll give it a shot once the rain washes the salt remnants off the road.

[Hib Halverson]

90s don't have valve stem seals on the exhaust, consequently, 90s tend to use oil and start to smoke much sooner in age than do 91-95.

While that blue smoke thing could be injectors–and you can determine if it is by running the fuel pressure tests in the FSM–it's possible that it may be time to pull the heads and have the intake valve seals replaced and have them installed on the exhausts.