Sump capacity vs. oil life via GM OLM

Joined
Aug 14, 2007
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207
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Patchogue, NY
Hello again BITOG, Yesterday I posted regarding my desire to begin following my OLM on my Pontiac G8-GT with the L-76 6.0L V8 with 8.8 quart sump. Right now the oil has about 5300 miles on it. This is the 2nd oil change, 1st was performed with about 1,250 miles on it. What concerns me is the OLM still shows 49% oil life left. The engine is spec'd to use dino oil. If I do the math, GM is saying they feel safe advocating a 10,000 mile OCI on dino oil? I'm actually getting the oil changed tomorrow over to synthetic so this is a moot point but I find that pretty interesting. Would that be due to the large sump capacity? Ed B.
 
Joined
Oct 9, 2004
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New Braunfels
THE GM OLM is the best one out there to date. You can trust it with conventional oil that meets the GM specs all the way down to 0%. ALot of folks run synthetic as a security blanket. I haven't seen an example where this system has been overly aggressive on the long side. If you check the oil every fill up like you are supposed to you will never have a problem following the OLM for the entire interval on any oil that meets the reqired spec. To tell the truth most over the counter synthetics have more detergents in them but not enough to significantly increase the OCI over a comparable conventional. To get a long drain oil you would need to purchase an oil specifically formulated for long drains. Appropriately formulated these oils will not meet the GM nor ILSAC GF 4 specs because often they need to add additives above the allowable limit for these specs to achieve that goal. Your OLM is calibrated to take into account the standard ILSAC GF 4 oils that are available everywhere. Nothing wrong with the OLM.. It is us AMericans who have a pshycological issue with it.
 

JHZR2

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Dec 14, 2002
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What is the sump capacity? Think about this: dino HDEOs have been used for years and years in OCIs that are tens of thousands of miles long... Nothing inherently wrong with dino oil when used in a situation where it is applied correctly. Ive seen very positive results using dino 10w-30 in 7500mi OCIs in various applications over time. No reason that 10k isnt doable with the right use profile and set-up. It might make sense to do a UOA even with syn oil in there to verify a few things such as staying in grade, fuel dilution, TBN retention and oxidation. This should settle most concerns.
 
Joined
Sep 23, 2006
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Bad Axe, MI
 Originally Posted By: JHZR2
What is the sump capacity?
8.8 quart sump OP i would follow the OLM with that much oil you'll be fine to 10K no problem.
 Originally Posted By: Bryanccfshr
THE GM OLM is the best one out there
yes it is,allot of testing went into it..
 
Joined
Jun 24, 2004
Messages
460
Location
Memphis, TN.
My Buick LuCerne with the Northstar V8 has a 7.5qt sump. I've been dumping the oil at about 10,000 miles and the OLM is still showing another 20-25% remaining service. Pretty much a 50/50 mix of city - hwy. I've been running either SuperTech 10w30 or Kendall 5w30 in it since new. Not a hint of a problem, no oil consumption, etc. Same mix of driving on my previous Buick Park Ave with the 3.8ltr and a 5 quart sump took me out to about 8,000 miles on the OLM before a change was needed. So sump capacity has to have something to do with it.
 
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Oct 10, 2008
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Sunny Florida
wonderful that it holds almost 9 quarts! I'd not seen that anywhere. Good for you. Because with that much oil on board the motor could run a LONG time on a good synthetic. 10k on good dino is easy. As a GM fleet owner I'd have to agree with the previous poster as to the accuracy of the GM OLM system. Our vans have a unique duty cycle including a lot of stationary operation, and it yields beautiful oil analysis on Amsoil 0W-30.
 
Joined
Sep 8, 2005
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15,229
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Canada
8.8 quarts! Egads that's a lot of oil! Compare that to a 1960's Pontiac 400 that might have had a 5-quart sump. No wonder engines didn't survive back then! Just on a personal note...I'm aware dino oil is perfectly acceptable for this application. However, if it were my car, and I'd spent good money on a V-8 muscle car, I'd spend the extra put synthetic in it. If for nothing else than the 'feel good' factor.
 

Win

Joined
Feb 5, 2003
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4,704
Location
Arkansas
I wouldn't worry about it, although I don't know how big an influence sump capacity has on the OLM. My G8 with the 3.6 is looking at an 11K+ OCI with a 7 quart sump. The Solstice looks like it will come in at about 9500 miles with a 5 quart sump 2.4 Ecotec. In contrast, my LS1 powered GTO would only go out to about 6K with a 6 quart sump. Every Jag I ever had specified a 10K mile OCI, even on the crummy (SF) older oils. They have had sumps ranging from 7 quarts for the late model V8's, to 8 to 12 quarts on the older 6's and 12's, so long OCI's are nothing new. If it really bothers you, just change it twice a year. That's what I do on my wife's Jag.
 
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