read the oil "101" - thinner oil really?
- Thread starter thesaint
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Should we? No, Can we? Maybe yes.
It is your engine so you {we} can do what we want. The oil should be thick enough to keep the parts seperated in the realistic worst conditions expected but not too thick as to cause too much power to pump it. so some times thinner oil works well ,some times maybe not???The 5w/20 oils seem to work fine for the engines that recommend them .Some other engines the 5w/20 work well some do not.
Good assessment. Your specific application is what counts.
aehaas
aehaas
Quote:
"Next let us look at a 20 weight oil at operating temperature. We get the same flow out of our constant volume pump but the thinner oil requires less pressure to move through the system. This even goes along with the rule that we should use an oil that gives us 10 PSI per 1,000 RPM:
(D) RPM....Pressure..Flow
1,000......10 PSI....1
2,000......20 PSI....2
4,000......40 PSI....4
8,000.. ...80 PSI....8
The maximum flow rate has not been reached. If the engine went to 9,000 RPM then the flow would be 9 at 90 PSI, our maximum pressure at pop off. The engine now has 3 times the flow rate as with the 40 weight oil at full RPM. The nozzles at the bottom of each cylinder are spraying 3 times the amount of oil lubricating and cooling this section. Everything runs cooler and the separation forces in the bearings are 3 times higher."
Sold! I feel better now knowing that 5w20 is in my CRV
So I now have my sights on a good 0w20 oil. Any current/updated recommendations Dr. Haas?
Thank you for a very informative read. Learned more in a couple of hours (had to put the kids to bed in between chapters) then browsing this site for past the 1.5 years... well I did get your link from this site, so not entirely true
I noticed the mention of Pennzoil dino 5w20. Would that apply to most 5w20 SM rated mineral based oils? Or is Pennzoil unique in some way?
"Next let us look at a 20 weight oil at operating temperature. We get the same flow out of our constant volume pump but the thinner oil requires less pressure to move through the system. This even goes along with the rule that we should use an oil that gives us 10 PSI per 1,000 RPM:
(D) RPM....Pressure..Flow
1,000......10 PSI....1
2,000......20 PSI....2
4,000......40 PSI....4
8,000.. ...80 PSI....8
The maximum flow rate has not been reached. If the engine went to 9,000 RPM then the flow would be 9 at 90 PSI, our maximum pressure at pop off. The engine now has 3 times the flow rate as with the 40 weight oil at full RPM. The nozzles at the bottom of each cylinder are spraying 3 times the amount of oil lubricating and cooling this section. Everything runs cooler and the separation forces in the bearings are 3 times higher."
Sold! I feel better now knowing that 5w20 is in my CRV
So I now have my sights on a good 0w20 oil. Any current/updated recommendations Dr. Haas?
Thank you for a very informative read. Learned more in a couple of hours (had to put the kids to bed in between chapters) then browsing this site for past the 1.5 years... well I did get your link from this site, so not entirely true
I noticed the mention of Pennzoil dino 5w20. Would that apply to most 5w20 SM rated mineral based oils? Or is Pennzoil unique in some way?
There is nothing unique on the Pennzoil. Many others do the job well.
aehaas
aehaas
its a good very long winded article and most people would be better off reading it than not, i have read it twice so far. but its a misleading article for the general public. for the audience in which it was intended (it was posted at a ferrari bbs) its fine perhaps.
the average schmuck has no expensive cars. the average schmuck has no oil pressure gauge, nor a temparture montoring device (i do haha). and possibly owns a high mileage car with an engine of unknown condition. so the average guy reads this article and decides to put some 5w20 in his beater trans am of the plastic body panel years (80's vintage) and promptly blows the engine.
this happen to my friend based on advice he read at this very website. his camshaft broke all the teeth off the cam gear a day after switching to 5w20 from 20w50. the teeth were all broken in 1 direction and now theres bits of cam teeth blown throughout the engine.
now he did follow the 10psi per 1000r's rule when hot. his car only revs up to 4500 r's before it yellow lines (this car has a yellow line and then a redline and he doesnt normally take it to redline ever.
so now im going to help him rebuild the engine because im his friend and i feel slightly responsible even though its his car and he made the decision. besies that, rebuilding old v8 motors is just plain fun
.
the average schmuck has no expensive cars. the average schmuck has no oil pressure gauge, nor a temparture montoring device (i do haha). and possibly owns a high mileage car with an engine of unknown condition. so the average guy reads this article and decides to put some 5w20 in his beater trans am of the plastic body panel years (80's vintage) and promptly blows the engine.
this happen to my friend based on advice he read at this very website. his camshaft broke all the teeth off the cam gear a day after switching to 5w20 from 20w50. the teeth were all broken in 1 direction and now theres bits of cam teeth blown throughout the engine.
now he did follow the 10psi per 1000r's rule when hot. his car only revs up to 4500 r's before it yellow lines (this car has a yellow line and then a redline and he doesnt normally take it to redline ever.
so now im going to help him rebuild the engine because im his friend and i feel slightly responsible even though its his car and he made the decision. besies that, rebuilding old v8 motors is just plain fun
.I guess there was quite a shock value for that cam gear going from 20W-50 all the way down to 5W-20.
For 7500, I think it is still highly regarded. The new hotness is the ASM (0W20), it should go longer than 7500 (but haven't had the chance to prove that personally in my vehicles yet)
""Everything runs cooler""
maybe depending on air flow and oil cooler if any extra flow may not cool better if heat has no where to go.
""and the separation forces in the bearings are 3 times higher""
Depends Oil pressure only pushes oil to bearing hydrodynamic wedge formation is dependant on crank rotating speed, bearing clearance and viscosity other than needing correct volume of oil, pressure and flow are not important.
bruce
maybe depending on air flow and oil cooler if any extra flow may not cool better if heat has no where to go.
""and the separation forces in the bearings are 3 times higher""
Depends Oil pressure only pushes oil to bearing hydrodynamic wedge formation is dependant on crank rotating speed, bearing clearance and viscosity other than needing correct volume of oil, pressure and flow are not important.
bruce
Still wonder about the engine that is lugged up a long hill towing a trailer? maybe not on purpose but because the engine has enough torque and the transmission allows it. Rpm is low, load on the bearings is high. Does the slow turning oil pump and thin oil feed the bearing enough film thickness? I know suburu engines converted for aircraft will wipe the bearings on (thin) oils that are fine in a car.
I'm with bruce381 on the hydrodynamic wedge formation. If an oil is too thin for a given bearing clearance, there's not going to be a hydrodynamic wedge formation and your crankshaft isn't going to be in suspension away from the crankshaft bearings.
Correct. The operating engine viscosity is dependent on your driving and engine parameters. But always use the lowest first number.
aehaas
aehaas
"Next let us look at a 20 weight oil at operating temperature.... 8,000.. ...80 PSI....8 The maximum flow rate has not been reached."
Is this extrapolated or measured ? Sustained speeds at 8000 rpm in a high output engine might generate a bit more heat then when putting around at 2000 to 3000 rpm in town.
Is this extrapolated or measured ? Sustained speeds at 8000 rpm in a high output engine might generate a bit more heat then when putting around at 2000 to 3000 rpm in town.
Flow does not guarantee hydrodynamic lubrication. Ditto what Bruce said.
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