This is just for discussion mind you not an attack or anyting like that!
In order for his articles to be right we would have to assume a lot of things.
1) All cars use the 10PSI per 1000 Rule in relation ship to oil pressure. Origanal rule was 25-45 PSI at Idle and 10 PSI for every additional 1000 RPMS.
2) All oil pumps have a poor ramp angle and can not handle thick fluids or self prime causeing cavitation and starvation.
3)All engines use the same clearances for pumps,gear and bearings.
4) All oil of like viscosity have the same HTHS or MOFT values.
5) His oil bypass rule is also not uniform in the real world.
6) The Porsche reason for not allowing 0W30 and 0W40 due to mineral VII's v.s. synthetics and droping bellow minimum viscoistys etc...
My take bellow:
1)We already know that Japanesse and Germany engine designs have histroicly followed the oil presure rule of thumb as listed. We also know that most American designs especialy GM have gone the other way and biased towards volume and not pressure and have in many cases ignored the golden rule.
2)If this was the case we would see a lot of oil pump failures. We would have a lot of start up knock and lifter tick. We would see signs of starvation like rod knock,scuffed pistons etc..
3) While clearances have not changed much we do know that their is a variance between manufactures. In some cases enough to warrant a thicker oil. We know that DC had to reclearance the oil pump on the 4.7V8 adn 3.7V6 when they switched from 10W30 to 5W30 as the recomended viscosity.
4) We know that this is not the case at all. We have my classic example of Redline 5W20 with an HTHS of 3.3 while some other 20Wt. oils are between 2.6 and 3.0. We even have some 30Wt. oils that have an HTHS of 3 like M1 0W30 and M1R wich have an HTHS of 2.9! We know that HTHS plays a large role in determining wear rates.
5) My Dodge Dakota did not bypass unti 110PSI even though the redline was around 5500RPM's-6000RPM's. If my memory serves me right bypass on my moms Tundra is 95PSI and I do not belive her truck revs much past 5500 RPM's. My Buick 3.8 will rev to5500 - 6000RPM's and it bypass's at 65PSI. Now understand that just becasue it bypass's at a cetain setting does not mean that the oil pressure will not exceed that psi!
6) Porsche does not recomend any mineral based oils at all. All oils on Porsches approved list are synthetic. It is true that Porsche makes no indication or different recomendation based on weather it is G-III or G-IV and V. We know that even premium synthetic 5W40 have about the same amount of VII's as a dino based 5W30 though. It could be that they are worried about the amounts of VII's that might be used to make a 0W30? We do know that all VII's are not created equaly!
We also know that many engine builders do not recomend high volume oil pumps unless the sump capacity is greatly increased for fear of uncovering the pickup. On the other hand GM Race Shop recomends shimming the stock volume oil pump to increase bypass presure to 95PSI and running a 20W50 oil on HO small blocks build up's.
Now Terry has repeatedly reminded me that we do not always need a liquid plastic to have protection! I agree!! I do think though that when going to either extreme either really thick or really thin one should work their way there with UOA as our guide. This is especialy true if you are going way outside of the recommended viscosity for your vechile! Now I am talking globably not just USA. We seem to get a different set of recomendations then the rest of the world. I also think that we need to concentrate more on the HTHS of the product then the Viscosity. HTHS can vary greatly from one product to the next of the same SAE viscosity.
I think Terry said it best when he recomended you start at 10W30 and work your way up or down from their. Run the thinest oil that UOA shows will work in your application.
For the record I have no problem with 20Wt. oils were they are recomended or where testing has proven them to work. I just have a problem with a blanket statement about 0W oil or blind recomendations with no data or personal experince to back it up. We have no one on this site that has either ran a 20Wt. in a Corvete or done a UOA of any GM engine with a 20Wt. We also have seen email messages from GM recomendeding against running a 20Wt. oil in their products!
It is not the 0W rather the 20Wt. part that has me concerned. I think it is easily accepted that a 0W30,0W40,0w20 can be run any place a 5W/10W-20,30,40Wt. can be run unless specificly not recomended by the OEM.
P.S. I have a 0W30 sample that will be sent in for UOA in march. I am hopeing it turns out well.
In order for his articles to be right we would have to assume a lot of things.
1) All cars use the 10PSI per 1000 Rule in relation ship to oil pressure. Origanal rule was 25-45 PSI at Idle and 10 PSI for every additional 1000 RPMS.
2) All oil pumps have a poor ramp angle and can not handle thick fluids or self prime causeing cavitation and starvation.
3)All engines use the same clearances for pumps,gear and bearings.
4) All oil of like viscosity have the same HTHS or MOFT values.
5) His oil bypass rule is also not uniform in the real world.
6) The Porsche reason for not allowing 0W30 and 0W40 due to mineral VII's v.s. synthetics and droping bellow minimum viscoistys etc...
My take bellow:
1)We already know that Japanesse and Germany engine designs have histroicly followed the oil presure rule of thumb as listed. We also know that most American designs especialy GM have gone the other way and biased towards volume and not pressure and have in many cases ignored the golden rule.
2)If this was the case we would see a lot of oil pump failures. We would have a lot of start up knock and lifter tick. We would see signs of starvation like rod knock,scuffed pistons etc..
3) While clearances have not changed much we do know that their is a variance between manufactures. In some cases enough to warrant a thicker oil. We know that DC had to reclearance the oil pump on the 4.7V8 adn 3.7V6 when they switched from 10W30 to 5W30 as the recomended viscosity.
4) We know that this is not the case at all. We have my classic example of Redline 5W20 with an HTHS of 3.3 while some other 20Wt. oils are between 2.6 and 3.0. We even have some 30Wt. oils that have an HTHS of 3 like M1 0W30 and M1R wich have an HTHS of 2.9! We know that HTHS plays a large role in determining wear rates.
5) My Dodge Dakota did not bypass unti 110PSI even though the redline was around 5500RPM's-6000RPM's. If my memory serves me right bypass on my moms Tundra is 95PSI and I do not belive her truck revs much past 5500 RPM's. My Buick 3.8 will rev to5500 - 6000RPM's and it bypass's at 65PSI. Now understand that just becasue it bypass's at a cetain setting does not mean that the oil pressure will not exceed that psi!
6) Porsche does not recomend any mineral based oils at all. All oils on Porsches approved list are synthetic. It is true that Porsche makes no indication or different recomendation based on weather it is G-III or G-IV and V. We know that even premium synthetic 5W40 have about the same amount of VII's as a dino based 5W30 though. It could be that they are worried about the amounts of VII's that might be used to make a 0W30? We do know that all VII's are not created equaly!
We also know that many engine builders do not recomend high volume oil pumps unless the sump capacity is greatly increased for fear of uncovering the pickup. On the other hand GM Race Shop recomends shimming the stock volume oil pump to increase bypass presure to 95PSI and running a 20W50 oil on HO small blocks build up's.
Now Terry has repeatedly reminded me that we do not always need a liquid plastic to have protection! I agree!! I do think though that when going to either extreme either really thick or really thin one should work their way there with UOA as our guide. This is especialy true if you are going way outside of the recommended viscosity for your vechile! Now I am talking globably not just USA. We seem to get a different set of recomendations then the rest of the world. I also think that we need to concentrate more on the HTHS of the product then the Viscosity. HTHS can vary greatly from one product to the next of the same SAE viscosity.
I think Terry said it best when he recomended you start at 10W30 and work your way up or down from their. Run the thinest oil that UOA shows will work in your application.
For the record I have no problem with 20Wt. oils were they are recomended or where testing has proven them to work. I just have a problem with a blanket statement about 0W oil or blind recomendations with no data or personal experince to back it up. We have no one on this site that has either ran a 20Wt. in a Corvete or done a UOA of any GM engine with a 20Wt. We also have seen email messages from GM recomendeding against running a 20Wt. oil in their products!
It is not the 0W rather the 20Wt. part that has me concerned. I think it is easily accepted that a 0W30,0W40,0w20 can be run any place a 5W/10W-20,30,40Wt. can be run unless specificly not recomended by the OEM.
P.S. I have a 0W30 sample that will be sent in for UOA in march. I am hopeing it turns out well.
