Is 20w 50 safe for a LT1?
Registered User
Joined: May 2007
Posts: 852
From: Apopka FL
well I went ahead and put the 20w 50 in since i already had it, I let it warm up and get completly hot, 30psi at idle 50psi at 6 grand. Is the oil pressure just telling me that the thicker oil is harder to push into all the bearings or is it oiling better? I guess if i spin a rod then running 20w 50 was'nt a good idea. But with 20psi I figured it's bound to happen anyway. The oil clearances worried me though, for the rods on a stock lt1 they are .0008 to .0022. would'nt everybody run 20w 50 if with 5w 30 they had 20 psi at 5 grand and with the heavy stuff you could get 50psi.
simple physics, try this - blow water through a straw then try some ice cream, which one do you thick will take more "pressure" to get through the straw?
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Joined: Dec 1969
Posts: 10,745
From: Buffalo, New York
well I went ahead and put the 20w 50 in since i already had it, I let it warm up and get completly hot, 30psi at idle 50psi at 6 grand. Is the oil pressure just telling me that the thicker oil is harder to push into all the bearings or is it oiling better? I guess if i spin a rod then running 20w 50 was'nt a good idea. But with 20psi I figured it's bound to happen anyway. The oil clearances worried me though, for the rods on a stock lt1 they are .0008 to .0022. would'nt everybody run 20w 50 if with 5w 30 they had 20 psi at 5 grand and with the heavy stuff you could get 50psi.
Rich
Registered User
Joined: Jul 2004
Posts: 3,034
From: Raleigh, NC
well I went ahead and put the 20w 50 in since i already had it, I let it warm up and get completly hot, 30psi at idle 50psi at 6 grand. Is the oil pressure just telling me that the thicker oil is harder to push into all the bearings or is it oiling better? I guess if i spin a rod then running 20w 50 was'nt a good idea. But with 20psi I figured it's bound to happen anyway. The oil clearances worried me though, for the rods on a stock lt1 they are .0008 to .0022. would'nt everybody run 20w 50 if with 5w 30 they had 20 psi at 5 grand and with the heavy stuff you could get 50psi.
Thread Starter
Registered User
Joined: Mar 2008
Posts: 147
From: central Arkansas
Its got the coolant lines runing to right on top of the oil filter, but no oil lines running to the radiator I have not looked at shoeboxes sight yet but i'll check it out. I think everyone is right on what they have said but again its a gamble for me, and I understand why the oil pressure is low, my engine has 117 miles of wide open throttle and I still can't beleive its still together, either way i'll run it as long as it's running strong and hopefully whenever it does come apart it does'nt completly shatter or spin the main bearings, around here it's like 250$ to get one align honed, and just 100$ to get one bored out. I will for sure let it warm up and I'm still don't feel 100% safe with it in their, I'm also sold that the lt1 is the most durable engine the general has ever put out. this engine has went to hell and back and still don't use a drop of oil, or smoke.
Registered User
Joined: Dec 2003
Posts: 477
From: Houston Tx
I've pretty much always used Mobil 15w-50 synthetic except when I was was in Wyoming during the winter. This car has been pushed over the years, and even at 185k miles doesnt consume any oil. I've had good experiences so I see no need to change.
Registered User
Joined: Dec 1969
Posts: 27,725
From: Little Rock, AR
Its got the coolant lines runing to right on top of the oil filter, but no oil lines running to the radiator I have not looked at shoeboxes sight yet but i'll check it out. I think everyone is right on what they have said but again its a gamble for me, and I understand why the oil pressure is low, my engine has 117 miles of wide open throttle and I still can't beleive its still together, either way i'll run it as long as it's running strong and hopefully whenever it does come apart it does'nt completly shatter or spin the main bearings, around here it's like 250$ to get one align honed, and just 100$ to get one bored out. I will for sure let it warm up and I'm still don't feel 100% safe with it in their, I'm also sold that the lt1 is the most durable engine the general has ever put out. this engine has went to hell and back and still don't use a drop of oil, or smoke.
Banned
Joined: Sep 2006
Posts: 1,478
oh well more then 20 4500lb 2ton beast running in 95 degree weather in traffic all day long with EXCELLENT OIL PRESSURES and no leaks are running down here on 20w-50 or thicker...never had a problem since more then 10 of them are running 50W beating the dog **** and cold starting them more then 20 times a day must be better then just one lucky car...i will stay with my statistics you keep reading your books i will go on 1st hand knowledge and experience...
and thnk you rkause for posting the link you did as that is the reason why i am running this weight on my TT b-body...
not everything has to be text book perfect....i guess its like pulling a 1qt of oil from the oil pan and the supposed 10HP increase from less oil splash on the crank if you think i am going to risk an engine just to gain 10hp then you have me bent.....id rather run my 50W keep to your books, unless you havent tried it then dont knock it TO EACH HIS OWN PAPA...
and thnk you rkause for posting the link you did as that is the reason why i am running this weight on my TT b-body...
not everything has to be text book perfect....i guess its like pulling a 1qt of oil from the oil pan and the supposed 10HP increase from less oil splash on the crank if you think i am going to risk an engine just to gain 10hp then you have me bent.....id rather run my 50W keep to your books, unless you havent tried it then dont knock it TO EACH HIS OWN PAPA...
Banned
Joined: Sep 2006
Posts: 1,478
coolant to the oil cooler huh that sucks i guess thats why they gave us b-bodies a 10x better oil cooling system then the coolant lines of glory flowing to your oil cooler adapter..lol hate to have a hose bust or a pin size hole in my metel tubing which goes all around the engine.
Registered User
Joined: Apr 2005
Posts: 1,546
From: Florence, Kentucky
I use a high volume pump, canton 7 qt pan, and thinner 10-30. I believe the higher volume is more important than the thicker weight and higher oil pressure for bearing cooling purposes and initial startup.
You can run just about any oil in your car and 99% of the time it will run just fine. I've seen old ladies that come in for an oil change after 30,000 miles
and their cars run just fine. Would I recommend this? No. But its just a good example of how forgiving small block oiling systems are.
So if you want to run 50W in your car it probably won't hurt a thing. Would I run it? No.
You can run just about any oil in your car and 99% of the time it will run just fine. I've seen old ladies that come in for an oil change after 30,000 miles
and their cars run just fine. Would I recommend this? No. But its just a good example of how forgiving small block oiling systems are.So if you want to run 50W in your car it probably won't hurt a thing. Would I run it? No.
Last edited by 97WS6Pilot; Jun 3, 2008 at 12:29 PM.
Registered User
Joined: Oct 2007
Posts: 1,174
10w-30 is no thicker than 5w-30 and often 0w-30s are thicker than the common choices in those other two weights so you certainly are confused.
I have run everything from 0w-30 to 15w-40, believe it or not overseas 15w-40 is what was recommended for the LT1. 5w-30 is a CAFE recommendation and if you bothered to open your owners manual you will find 10w-30 is approved down to 0F.
rkrause wrote up a good thread on oiling in the advanced section some time ago, think it is worth a read for most of you. You would understand that the oiling system does not need pressure, it needs VOLUME and that we just use pressure gauges because it is easier to measure. It is NOT oil pressure that keeps parts separated it is basically hydroplaning. Once you hit bypass pressure for the oil pump relief spring oil starts to just recirculate from the pressure side of the pump to the intake side meaning no additional volume of oil is making it through the bearings.
IMO based on my understanding having the oil so thick it maxes out the bypass spring by just a few thousand rpms is a bad thing because you endup recirculating and heating a lot of oil within the pump and no additional volume is moved across the bearings to cool them.
Far as anecdotal evidence I have known people who put 1 quart of gear lube in engines at every oil change and the engines survived, does not mean the gear lube helped anything and does not even mean it was harmless.
I have run everything from 0w-30 to 15w-40, believe it or not overseas 15w-40 is what was recommended for the LT1. 5w-30 is a CAFE recommendation and if you bothered to open your owners manual you will find 10w-30 is approved down to 0F.
rkrause wrote up a good thread on oiling in the advanced section some time ago, think it is worth a read for most of you. You would understand that the oiling system does not need pressure, it needs VOLUME and that we just use pressure gauges because it is easier to measure. It is NOT oil pressure that keeps parts separated it is basically hydroplaning. Once you hit bypass pressure for the oil pump relief spring oil starts to just recirculate from the pressure side of the pump to the intake side meaning no additional volume of oil is making it through the bearings.
IMO based on my understanding having the oil so thick it maxes out the bypass spring by just a few thousand rpms is a bad thing because you endup recirculating and heating a lot of oil within the pump and no additional volume is moved across the bearings to cool them.
Far as anecdotal evidence I have known people who put 1 quart of gear lube in engines at every oil change and the engines survived, does not mean the gear lube helped anything and does not even mean it was harmless.
Administrator
Joined: Nov 1998
Posts: 71,094
From: Hell was full so they sent me to NJ
Don't read your book (Owner's Manual)... what do GM engineers know? They are just trying to make your engine fail, so they can sell more overpriced spare parts. Run that straight 50 weight....
Sure.....
Really sorry I wasted all those years getting my mechanical engineering degree, learning all about lubrication and bearing design, running lab projects to demonstrate the principles being taught, and then working for 7 years in the Research & Engineering center of one of the world's largest oil companies. But wait... oil company's are in on the conspiracy to ruin our engines.
LOL
Sure.....
Really sorry I wasted all those years getting my mechanical engineering degree, learning all about lubrication and bearing design, running lab projects to demonstrate the principles being taught, and then working for 7 years in the Research & Engineering center of one of the world's largest oil companies. But wait... oil company's are in on the conspiracy to ruin our engines.
LOL
Thread Starter
Registered User
Joined: Mar 2008
Posts: 147
From: central Arkansas
Do you really think running the 20w 50 is a horrible idea? I'm no pro on oil and even engine building or bearing clearances but if i have 20psi at 5 grand that tells me that the oil is being pushed past the bearings to easy, and the heavier oil will slow down that process causing the higher oil pressure reading. Am i on the right page or not? All i want is for my engine to last as long as it can for the least amount of dollar invested. How wide are the clearances on the bearings for you guys running the 50 weight?
Moderator
Joined: Dec 1969
Posts: 10,745
From: Buffalo, New York
Do you really think running the 20w 50 is a horrible idea? I'm no pro on oil and even engine building or bearing clearances but if i have 20psi at 5 grand that tells me that the oil is being pushed past the bearings to easy, and the heavier oil will slow down that process causing the higher oil pressure reading. Am i on the right page or not? All i want is for my engine to last as long as it can for the least amount of dollar invested. How wide are the clearances on the bearings for you guys running the 50 weight?
Rich
Administrator
Joined: Nov 1998
Posts: 71,094
From: Hell was full so they sent me to NJ
Do you really think running the 20w 50 is a horrible idea? I'm no pro on oil and even engine building or bearing clearances but if i have 20psi at 5 grand that tells me that the oil is being pushed past the bearings to easy, and the heavier oil will slow down that process causing the higher oil pressure reading. Am i on the right page or not? All i want is for my engine to last as long as it can for the least amount of dollar invested. How wide are the clearances on the bearings for you guys running the 50 weight?
Will it "ruin" your engine - probably not. Will it benefit it - definitely not. Do not confuse high oil pressure with superior lubrication. It will increase cold start wear. It will take more HP to pump. It will increase the load on the plastic components in the LT1 oil pump drive. It will reduce fuel MPG slightly.
Rather than run heavier oil to cover up the problem, why not repair the engine. And, under no circumstances should you even think about running straight SAE 50 oil in your stock bottom end LT1.