96 FZJ80 Oil/Coolant Consumption

[DaveInDenver]

I think history has shown folks that they have a reduction in oil loss when using higher viscosity oils. So that’s another factor besides lubrication.

My 1FZ-FE engines get Mobil - 5W-30 high mileage. Available at Costco FWIW. The white turbocruiser with 100,000 miles on a Robbie head rebuild burns nothing. The green turbeaucruiser burns about a quart every 5,000 miles, which I’m pretty sure is valve stem seals.

I'm 100% in agreement. I run 5W30 in our Subaru rather than the factory recommended 0W20 and consumption in a notoriously badly consuming engine is low and wear indicators come back just fine. The engine also sounds better but that's not a qualified measurement.

While straying from 5W40 euro-spec on the VW was a huge consumption mistake and that was when it had low miles. The question may not be simple. Like the VW consumption seemed to be in the PCV system (there was white gooey sludge in the intake), not past the rings or HG like it seems to be with Subarus.

I do love Toyotas. I've never really had to much think about it. I run 10W30 in the 22R and 22R-E and 5W30 in the Tacoma and I've never really seen any evidence it mattered. My 1991 22R-E had that timing chain failure but that was a defective tensioner that I'm reasonably sure had nothing to do with oil (although arguably could, it's actuated by oil pressure). HG failures, that's probably more coolant corrosion than oil related. None of my Toyota engines, even the 2F, I felt leaked or consumed excessively (a non-distinct qualifier fer sure).

I'd also just mention that a lot of this is anecdotal. You always get someone saying "I did exactly what the factory said, 0W20 and 10K intervals and I have 300,000 miles on the engine." to disprove the whole second guessing of the engineers we do. While plenty of people follow the book to the letter and have early failures, so the whole question never really resolves.

I think some of this has to do with environment. Living here in GJ the dust and heat is quite a bit different than even you guys in Denver and certainly someone living in Leadville isn't going to want to run hot weather oils like I do.

 

[Rzeppa]

Right, I know that's the theory but does that actually happen?

It does according to my gauge.

So is going to thicker oil a placebo effect? When the needle on the oil pressure gage points higher we think that is better. But in fact the ideal pressure may be nearly zero when you consider that pressure is building as the result of fluid's resistance to flow (e.g. is it psi or GPM that's important?). Wouldn't higher viscosity = lower volume of oil circulating? Could that work against you and accelerate wear? Particularly if you have uneven bearing wear. So if you have say one bearing with more wear where thicker oil does help compensate but are you harming the others where it's not needed by slightly starving them?

What you want is a film (more than one molecule thick!!!) between the bearing and whatever surface it is sliding along. Thinner oil makes that film thinner. The reason that most wear occurs during start up is that there is no oil pressure!

Less thought-about is the oil circulation also wicks some heat away from heat-producing parts, and then we want to cool the oil, hence the oil cooler in all 2Fs since 1976, which dumps that heat into the cooling system.