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Lowest Viscosity an Engine can be safely operated
- Thread starter FMC
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"Lowest Viscosity an Engine can be safely operated"
This depends somewhat on how long you intend to operate said engine, type of engine, environment, engine condition, etc.
You could probably operate on sewing machine oil or thinner for a few minutes.
This depends somewhat on how long you intend to operate said engine, type of engine, environment, engine condition, etc.
You could probably operate on sewing machine oil or thinner for a few minutes.
If you believe lube-related infomercials, you can run a racing engine at high RPM's on Dura-Lube for 2 minutes without any oil. That breaks down to a 0w-.000001 I think.
Who would not believe that...
Originally Posted By: river_rat
Wolfs Head 5W-20, I believe it is, lists like 6.8. Pretty thin.
Yes but it must have a HTHS vis of 2.6cP which means it's actual operational viscosity is no lighter than any other 2.6cP 20wt oil.
Honestly I doubt the presumably GP III based Wolfshead has a KV100 spec' that low. Royal Purple's XPR 5W-20 race oil has a KV100 also of 6.8cSt and it's a PAO/Ester based oil and I even take that figure with a grain of salt, so to speak. Anyway it's all academic as it is the HTHS vis that is the true measure of how think or thin an oil is at normal operating temperatures.
Wolfs Head 5W-20, I believe it is, lists like 6.8. Pretty thin.
Yes but it must have a HTHS vis of 2.6cP which means it's actual operational viscosity is no lighter than any other 2.6cP 20wt oil.
Honestly I doubt the presumably GP III based Wolfshead has a KV100 spec' that low. Royal Purple's XPR 5W-20 race oil has a KV100 also of 6.8cSt and it's a PAO/Ester based oil and I even take that figure with a grain of salt, so to speak. Anyway it's all academic as it is the HTHS vis that is the true measure of how think or thin an oil is at normal operating temperatures.
Right...HTHS is the real deal, and they have to test at least 2.6 to be licenses as a 20 wt. An they may have made a typo. Their 5W-30 is right in the average range.
So I guess the answer to the OP is whatever weight the has minimum of an 2.6 CP HTHS viscosity, or whatever HTHS has proven to be safe for the engine life and driving conditions you desire and expect.
So I guess the answer to the OP is whatever weight the has minimum of an 2.6 CP HTHS viscosity, or whatever HTHS has proven to be safe for the engine life and driving conditions you desire and expect.
Originally Posted By: FMC
Normal daily driving, 50/50 highway/city, east coast temp ranges 10 to 100 degrees
The limiting factor on how light an oil you can run is the minimum oil pressure that's specified for your engine. Your engine has no idea of the grade or viscosity spec's of the oil you're running, all it knows at any give time is what the operational viscosity is and the best proxy for that is the engine's oil pressure. So to determine that you need to install an accurate OP gauge.
The lightest SM/SN oils you can buy are the Japanese OEM 0W-20's such as the Toyota Brand OW-20 and Honda Brand 0W-20.
Even these oils will be thicker than optimum in every engine until the oil temp's get up to at least 75C-80C. If your oil temp's get higher than that, that's where the OP gauge will tell you if your OP is getting too low as the oil continues to thin with higher oil temp's.
Normal daily driving, 50/50 highway/city, east coast temp ranges 10 to 100 degrees
The limiting factor on how light an oil you can run is the minimum oil pressure that's specified for your engine. Your engine has no idea of the grade or viscosity spec's of the oil you're running, all it knows at any give time is what the operational viscosity is and the best proxy for that is the engine's oil pressure. So to determine that you need to install an accurate OP gauge.
The lightest SM/SN oils you can buy are the Japanese OEM 0W-20's such as the Toyota Brand OW-20 and Honda Brand 0W-20.
Even these oils will be thicker than optimum in every engine until the oil temp's get up to at least 75C-80C. If your oil temp's get higher than that, that's where the OP gauge will tell you if your OP is getting too low as the oil continues to thin with higher oil temp's.
Originally Posted By: river_rat
An they may have made a typo. Their 5W-30 is right in the average range.
I suspect it is a typo and Wolfshead's KV100 spec' is 8.6cSt instead of 6.8cSt. This would be consistent with other GP III, VII containing 5W-20 oils.
An they may have made a typo. Their 5W-30 is right in the average range.
I suspect it is a typo and Wolfshead's KV100 spec' is 8.6cSt instead of 6.8cSt. This would be consistent with other GP III, VII containing 5W-20 oils.
How thin you can go depends on engine.
0w and 5w oil needs to be at least 3.8cst
A 0w20 needs to be at least 5.6cst
RP also has a pseudo 0w5 oil since the suffix 5 isn't in sae J300.
Redline racing: too thick for us
JoeGibbs has a '0' racing oil that is 3.3cst.
Many non-SAE, make believe, weights exist. You'll need to contact the manufacturer for data.
0w and 5w oil needs to be at least 3.8cst
A 0w20 needs to be at least 5.6cst
RP also has a pseudo 0w5 oil since the suffix 5 isn't in sae J300.
Redline racing: too thick for us
JoeGibbs has a '0' racing oil that is 3.3cst.
Many non-SAE, make believe, weights exist. You'll need to contact the manufacturer for data.
Originally Posted By: FMC
Normal daily driving, 50/50 highway/city, east coast temp ranges 10 to 100 degrees
Can this car be safely operated running 5w-20 year round? 5w-30?
Normal daily driving, 50/50 highway/city, east coast temp ranges 10 to 100 degrees
Can this car be safely operated running 5w-20 year round? 5w-30?
Last edited:
The question is really, how long or how many miles will the engine run, whitout serious wear problems. I don't want to spend the time or money to wear out my engine to find out.
Originally Posted By: Eddie
The question is really, how long or how many miles will the engine run, whitout serious wear problems. I don't want to spend the time or money to wear out my engine to find out.
You don't have to.
With all the UOAs posted here, show me just one that clearly indicates the oil was too light resulting in obvious evidence of bearing wiping? I haven't seen one yet.
The truth is, any OTC 0W-20 or 5W-20 will not be too light in 99.99% of all street driven cars in NA. Even if you try to run an oil that you think will be too light it is very difficult to do so without resorting to some sort of extreme engine abuse.
The question is really, how long or how many miles will the engine run, whitout serious wear problems. I don't want to spend the time or money to wear out my engine to find out.
You don't have to.
With all the UOAs posted here, show me just one that clearly indicates the oil was too light resulting in obvious evidence of bearing wiping? I haven't seen one yet.
The truth is, any OTC 0W-20 or 5W-20 will not be too light in 99.99% of all street driven cars in NA. Even if you try to run an oil that you think will be too light it is very difficult to do so without resorting to some sort of extreme engine abuse.
Tap water.
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Too light of an oil and you can spin a bearing.
If you get it hot enough, for sure even the recommended oil will get too thin.
Same thing is there is a mechanical problem and too much fuel gets in the oil.
But normally, recommended oils have a great range of safe operating characteristics.
Same thing is there is a mechanical problem and too much fuel gets in the oil.
But normally, recommended oils have a great range of safe operating characteristics.
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