Lake Speed jr. Thick vs. Thin video.

[ZeeOSix]

Wouldn't this be even more true if the oil pump mapping as well as bearing clearances weren't suitable for the grade in question?

Journal bearing clearances in mass produced engines have been as tight as they can go for decades. At some point the clearance can't be made any smaller because the bearing will run too hot and destroy itself. No oil pump is mapped based on the journal bearing clearances. As mentioned in post 40 ( LINK ), using a thinner oil in bearings with lots of clearance is more detrimental than running thicker oil in tighter clearances. That's why Driven and others recommended using thicker oil when the journal bearing clearances are greater. Running a 0W-20 in loose bearings isn't a good idea. Running a 0W-40 in tight bearings works fine.

 

[BMWTurboDzl]

Journal bearing clearances in mass produced engines have been as tight as they can go for decades. At some point the clearance can't be made any smaller because the bearing will run too hot and destroy itself. No oil pump is mapped based on the journal bearing clearances. As mentioned in post 40 ( LINK ), using a thinner oil in bearings with lots of clearance is more detrimental than running thicker oil in tighter clearances. That's why Driven and others recommended using thicker oil when the journal bearing clearances are greater. Running a 0W-20 in loose bearings isn't a good idea. Running a 0W-40 in tight bearings works fine.

I'm beginning to think the test engine was a ringer.

 

[ZeeOSix]

I'm beginning to think the test engine was a ringer.

It was mentioned that if that engine had bearing clearances on the "loose" side, that running the thinner oil would give less hydrodynamic MOFT, meaning more risk of the MOFT going to zero if pushed too hard and be more detrimental than the thicker oil, as shown in post 40.

 

[travis8352]

Lol, FordBossMe is down there below PF on my list of people to take serious advice from.

PF is molakule compared to fordbossme lol

 

[Accent Abuser]

Journal bearing clearances in mass produced engines have been as tight as they can go for decades. At some point the clearance can't be made any smaller because the bearing will run too hot and destroy itself. No oil pump is mapped based on the journal bearing clearances. As mentioned in post 40 ( LINK ), using a thinner oil in bearings with lots of clearance is more detrimental than running thicker oil in tighter clearances. That's why Driven and others recommended using thicker oil when the journal bearing clearances are greater. Running a 0W-20 in loose bearings isn't a good idea. Running a 0W-40 in tight bearings works fine.

Heck I run 15w-50 with a .0020 rod bearing clearance and a .0017 main bearing clearance. Pretty much any modern engine is going to fall in that range. I get instant oil flow to the valve train on startup and the last time I was in there everything looked brand new, even the coating on the valve buckets looked untouched.

 

[ProbeGT]

Heck I run 15w-50 with a .0020 rod bearing clearance and a .0017 main bearing clearance. Pretty much any modern engine is going to fall in that range. I get instant oil flow to the valve train on startup and the last time I was in there everything looked brand new, even the coating on the valve buckets looked untouched.

Specs for my Toyota/Yamaha 2ZZ-GE are 0.0011 – 0.0020 in. rod bearing clearance and 0.0006 – 0.0013 in. main bearing clearance. Do clearances get any tighter than that in newer engines? Recommended oil varies depending on car. 5W-30 API-SL in FWD Corolla/Matrix/Vibe/Celica, 5W-40 API-SL in mid-engine MRS/Lotus Elise.

I switched to 0W-40 in both cars since the "modern", "energy-conserving" 5W-30 API-SN oil wiped my intake cam a few years ago. The thicker oil seems to have no downsides. From now on, all my cars and those I maintain will be getting oil at least one grade thicker than the owner's manual recommends.