Is 20w 50 safe
06-03-2017, 04:48 PM
#1
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Join Date: Aug 2009
Location: las vegas
Posts: 764
Is 20w 50 safe
Hey guys my co worker bought a 94 lt1 camaro z28 a4,long tube headers,pretty much everything is stock,everything is great,he changed the oil,but is using 10w 40 STP brand fully synthetic.
but one of his friends said to use 20w 50 bcuz the heat here gets to over 100, but I told him let me ask you guys on what think. I told him I'm using mobile one 10 40 but his friends said I'm not using the right weight n says my engine will get messed up lol.
I told him not gonna argue about it so I'll throw it to u guys. Btw i forgot to get this in
currently has 140xxx miles,n his oil pressure is like 20 to 15 psi after fully hot n running temperature
but one of his friends said to use 20w 50 bcuz the heat here gets to over 100, but I told him let me ask you guys on what think. I told him I'm using mobile one 10 40 but his friends said I'm not using the right weight n says my engine will get messed up lol.
I told him not gonna argue about it so I'll throw it to u guys. Btw i forgot to get this in
currently has 140xxx miles,n his oil pressure is like 20 to 15 psi after fully hot n running temperature
Last edited by 94Z28LS1toLT1; 06-03-2017 at 05:02 PM.
06-03-2017, 06:18 PM
#3
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Join Date: Nov 1998
Location: Hell was full so they sent me to NJ
Posts: 70,648
Re: Is 20w 50 safe
Unless the engine has been rebuilt to non-stock specifications, use what the factory recommends. The first # tells you how well the oil will flow on a cold start. That's when most of the engine wear occurs. ”5W" or "10W" tells you the oil will flow well when it's cold. "20W" as the first number tells you it will not flow as well.
It's the second number that tells you the thickness of the oil when it's hot (212*F). Even though the air temp may be higher where you live, the oil temperature is what is important. The cooling system is designed to control that temperature, regardless of the air temp, and the oil temp closely mirrors coolant temp with the LT1's reverse flow cooling system.
GM feels "30" provides the best combination of flowability and film thickness under pressure. "50” doesn't flow as well. Good oil flow also removes heat from the critical bearing surfaces. Better flow results in cooler oil.
All that said, GM recommends (read your Owner's Manual) 5W-30 multi-viscosity oil. They also indicate if the ambient air temp will not drop below 0*F, 10W-30 is acceptable. You don't need the "5W" flowability until temp drops below 0*.
The ultimate answer lies in used oil analysis. The only way to know what is best for your engine.... see "bobistheoilguy" website. People who have relied on UOA with the LT1 have found that Mobil-1 10W-30 meets the specifications for "30 weight" oil when hot, but the viscosity is toward the low end range of the spec. They found better results with a German Castrol 10W-30 because it's measured viscosity tended toward the higher end of the 30-weight range.
The above is sort of old news, and some additional research may be necessary to find the best 5W-30 or 10W-30 UOA results. But, all things considered, for a stock internal LT1 in good condition, 20W-50 would be a serious mistake.
A performance rebuild is a different story. The engine builder should tell you what to run. My builder actually told me to run a specific 25W-50 racing oil, when spraying a 300-shot (800 HP at the flywheel, 7,200 RPM redline). But he also cautioned that for winter driving to run a specific turbo-rated 10W-30 to avoid cold engine wear.
It's the second number that tells you the thickness of the oil when it's hot (212*F). Even though the air temp may be higher where you live, the oil temperature is what is important. The cooling system is designed to control that temperature, regardless of the air temp, and the oil temp closely mirrors coolant temp with the LT1's reverse flow cooling system.
GM feels "30" provides the best combination of flowability and film thickness under pressure. "50” doesn't flow as well. Good oil flow also removes heat from the critical bearing surfaces. Better flow results in cooler oil.
All that said, GM recommends (read your Owner's Manual) 5W-30 multi-viscosity oil. They also indicate if the ambient air temp will not drop below 0*F, 10W-30 is acceptable. You don't need the "5W" flowability until temp drops below 0*.
The ultimate answer lies in used oil analysis. The only way to know what is best for your engine.... see "bobistheoilguy" website. People who have relied on UOA with the LT1 have found that Mobil-1 10W-30 meets the specifications for "30 weight" oil when hot, but the viscosity is toward the low end range of the spec. They found better results with a German Castrol 10W-30 because it's measured viscosity tended toward the higher end of the 30-weight range.
The above is sort of old news, and some additional research may be necessary to find the best 5W-30 or 10W-30 UOA results. But, all things considered, for a stock internal LT1 in good condition, 20W-50 would be a serious mistake.
A performance rebuild is a different story. The engine builder should tell you what to run. My builder actually told me to run a specific 25W-50 racing oil, when spraying a 300-shot (800 HP at the flywheel, 7,200 RPM redline). But he also cautioned that for winter driving to run a specific turbo-rated 10W-30 to avoid cold engine wear.
Last edited by Injuneer; 06-03-2017 at 06:29 PM.
06-04-2017, 02:24 PM
#4
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Join Date: Jun 2003
Posts: 1,083
Re: Is 20w 50 safe
OP
unless your friends motor was rebuilt with wider bearing clearances....use 5 or 10-30
Motors built with wider bearing clearances, like mine and others like Injuneer's, can use 20-50 as per builders spec. I use 10-40 in Winter
unless your friends motor was rebuilt with wider bearing clearances....use 5 or 10-30
Motors built with wider bearing clearances, like mine and others like Injuneer's, can use 20-50 as per builders spec. I use 10-40 in Winter