5w-20 oil and engine lugging

[ToyotaNSaturn]

Recently, there was a post (UOA?) of 5w-20 oils and increased wear when the engine was lugged around at low RPM's. IIRC, this was peformed on a Ford truck... Anyone find this thread? Honda calls for 5w-20 in the latest 3.5L V6 models, I have an '04 with 2500 miles on it. I noticed how low the RPMS are when going through some of the hills around here...1000-1100RPM. It produces a decent amount of torque that low, but it strains the engine until it downshifts. The trans will downshift as expected, but I just don't like the fact that 5w-20 oil is in this thing when it's being revved so low. 5w-30 it is!

 

[Kestas]

It makes sense. Lugging is a low rpm condition. Low rpms develop less hydrodynamic wedge lubrication (or whatever the technical term is) which is more difficult for a thin oil to develop. Lugging is also hard on the crankshaft itself. The crank can develop cracks at the journal fillets, eventually splitting in two or three pieces.

 

[Jay]

There is only one 5w-20 report that shows increased lead wear and that was in TooSlick's 2.4L Toyota Tacoma where 20-weight wasn't the recommended viscosity. He tried two 20-weight oils and found increased lead with both. The automatic in my Acura RSX "lugs" the engine to get good gas mileage and my lead was 0ppm in a 7,000 mi interval with M1 0w-20. All other wear metals were below 1ppm/1000mi. There are many other examples of low rpm engines doing extremely well on 5w-20 (like mscales V-10 truck). Do a search and read the reports.