For those that use oil...

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Originally Posted By: fenixguy
Originally Posted By: fdcg27
1 is fine.
If manufacturers thought that adds in smaller increments were desirable, they'd have the safe range marked accordingly.


Bingo. That's why it's called the acceptable range.


I have to agree here as well. When the wife's caddy got a new engine it was using some oil. What I couldn't believe was how accurate the idiot oil light was, when it came on it was always right at the L or 1 mark. So I have to believe they know what they're doing.
 
Although I used to do it myself, I don't understand the obsession of keeping oil up to the full mark all the time when the manufacturer is happy as long as it's above L.

I do a 12 month 4000 mile OCI on an engine that burns a negligible amount. In those circumstances I consider filling above 1 at the OCI to be a waste of good oil when from experience I know that without any top ups it will still be above L at the next change.
 
Originally Posted By: Duffyjr
Originally Posted By: fenixguy
Originally Posted By: fdcg27
1 is fine.
If manufacturers thought that adds in smaller increments were desirable, they'd have the safe range marked accordingly.


Bingo. That's why it's called the acceptable range.


I have to agree here as well. When the wife's caddy got a new engine it was using some oil. What I couldn't believe was how accurate the idiot oil light was, when it came on it was always right at the L or 1 mark. So I have to believe they know what they're doing.


I have to assume that the reason the idiot light goes on the L or 1 is the oil pressure has reached a unsafe low pressure,(not good) that would mean keeping your oil closest to the full mark gives you the optimal oil pressure...somewhere in that safe range the oil pressure may still be lower than when full, the guy's with real oil gauges could confirm this...
 
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The oil level won't directly affect pressure unless there isn't enough oil to keep the oil pickup covered.

The oil would run hotter and would thin, I could see a slight difference in pressure from that.
 
Originally Posted By: rollinpete
Originally Posted By: Duffyjr
Originally Posted By: fenixguy
Originally Posted By: fdcg27
1 is fine.
If manufacturers thought that adds in smaller increments were desirable, they'd have the safe range marked accordingly.


Bingo. That's why it's called the acceptable range.


I have to agree here as well. When the wife's caddy got a new engine it was using some oil. What I couldn't believe was how accurate the idiot oil light was, when it came on it was always right at the L or 1 mark. So I have to believe they know what they're doing.


I have to assume that the reason the idiot light goes on the L or 1 is the oil pressure has reached a unsafe low pressure,(not good) that would mean keeping your oil closest to the full mark gives you the optimal oil pressure...somewhere in that safe range the oil pressure may still be lower than when full, the guy's with real oil gauges could confirm this...


You would be making an incorrect assumption.
Some cars have an oil level light and this Caddy happens to be one of them.
As Silver noted, oil level doesn't affect oil pressure unless it's so low that the oil pump pickup sucks air, which happens only when down below a couple of quarts in the sump typically.
Bulk oil temperature is probably not affected by oil quantity in that a steady state temperature is reached in either case but will get there more quickly at a lower sump level.
 
Originally Posted By: fdcg27
Originally Posted By: rollinpete
Originally Posted By: Duffyjr
Originally Posted By: fenixguy
fdcg27 said:
1 is fine.
If manufacturers thought that adds in smaller increments were desirable, they'd have the safe range marked accordingly.

Bingo. That's why it's called the acceptable range.


I have to agree here as well. When the wife's caddy got a new engine it was using some oil. What I couldn't believe was how accurate the idiot oil light was, when it came on it was always right at the L or 1 mark. So I have to believe they know what they're doing.


I have to assume that the reason the idiot light goes on the L or 1 is the oil pressure has reached a unsafe low pressure,(not good) that would mean keeping your oil closest to the full mark gives you the optimal oil pressure...somewhere in that safe range the oil pressure may still be lower than when full, the guy's with real oil gauges could confirm this...


You would be making an incorrect assumption.
Some cars have an oil level light and this Caddy happens to be one of them.
As Silver noted, oil level doesn't affect oil pressure unless it's so low that the oil pump pickup sucks air, which happens only when down below a couple of quarts in the sump typically.
Bulk oil temperature is probably not affected by oil quantity in that a steady state temperature is reached in either case but will get there more quickly at a lower sump level.




Thanks that makes sense...
 
Originally Posted By: fenixguy
Originally Posted By: fdcg27
1 is fine.
If manufacturers thought that adds in smaller increments were desirable, they'd have the safe range marked accordingly.


Bingo. That's why it's called the acceptable range.



"Acceptable" does not equal "design" or even "optimum." Ask those same engineers what the difference is between those 3 levels. Acceptable is probably for those owners who are lucky to even check their oil between OCI's, or never do it themselves. They are considering the lowest acceptable level of car from the "typical" owner. That's not anyone on this site. Acceptable level will easily get you through the mfg's engine warranty period...and probably well past 100K miles. Is it ideal for obtaining the maximum life of the engine...probably not. The engineers designed and tested the car at the "full" mark....except possibly through a specific "low oil level" test. If "Full" wasn't where they wanted the car when delivered new, then they would have shipped it with the oil at the "L" mark.

I do a lot of "acceptable" things when maintaining and servicing my cars....such as never claying the finish. Frequent washings and 2X yearly waxings have given me "acceptable" finish life on cars in the back end of their lives. I don't do a lot in cleaning my interiors (vacuuming and wiping down stains when they occur is about it). But when it comes to engine/transmission/rear end care, "acceptable" is not good enough considering a repair/replacement can run you $thousands. Those are the only repair bills on my cars that I consider "unacceptable."
 
The only time I pull the dipstick is at oil change time (every 5.5k mi/9k km, matches what the OLM says). Before I drain the oil I check to see how much oil has been burnt and after pouring in 4.3 l of oil, I check the dipstick to make sure the level is at the Full mark. The level drops to about 2 by oil change time. I never top up the oil between changes. Been doing it this way for the last thirty years.

I only do this because I am the only one driving this truck and would notice any oil leaks or smoke, indicating oil burning. Also the GM 4.3 V6 has a reputation for being a very reliable engine. I have complete and utter confidence in this engine and trust it to keep running without any issues. On the other hand I have less confidence in the all plastic clutch hydraulics which failed me once and I had to get my truck towed to my house.

My theory is that there is a bit of margin built in with oil level markings on the dipstick. At Full level there is a bit of extra oil there leading to some churning.
 
Had a 2000 Chevy Impala that would burn oil. I'd add whenever the oil pressure light would come on if I made a hard brake or sudden turn.
 
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