Are thinner oils about fuel economy or tighter engines?

Status
Not open for further replies.
Both. There is no dispute that newer = tighter tolerances. Thinner oils flow faster into these smaller spaces and hydrodynamic oil separation of moving parts occurs faster. IF heat is well managed, these thinner oil films won't turn into coked brown clogged messes.
Tighter tolerances in manufacturing, but not tighter clearances with regard to engine specs.
 
Screenshot_20230517_121730.jpg
 
Once again: Both. This is normal in almost all industries, when I was in metal stampings, the push was always to have machining tolerances at stamped metal prices. Computer memory is another example..
Which engine clearances are tighter? Clearance is still relative to bore size/bearing journal size and metal expansion with heat. I don't see clearances tighter than in the past. Probably with piston ring lands higher on the pistons in the last 20 years or so, there may be more piston ring end gap than in the past.
 
Always thought it was only about fuel economy but with better manufacturing techniques and wanting better performance squeezed out of engines could it involve tighter tolerances as well?

Your thoughts?
Define tighter engines.
 
I have a 2011 1GR-FE engine that calls for 0W-20. Some 2010 versions of 1GR-FE use 5W-30. I found no differences in part numbers for the crankshaft, main bearings, rod bearings, camshaft, cam bearings, pistons, piston rings, oil pump and VVTi. I live in a hot climate and decided to use 5W-30 instead of 0W-20.
 
The whole tighter clearance thing is utter nonsense. Why would Toyota spec their engines outside of the US to show everything from 20w-50 down to 0w-20 when 20w-50 is too thick for an engine "designed" for 20. It's the US's wonderful regulations.

Did a change on my 2021 escalade just yesterday. Almost forgot how watery that pure 0w-20 comes out compared to 15w-40. Ended up putting a blend of both in, last time I'll ever run anything below 30. Engine only has 14k on it yet it burned a quart and a half during the 7k interval. That much consumption in a new engine is unacceptable. Didn't tow or drive it hard. Doubt the stealer would do anything. They'll likely say some nonsense about a quart every thousand being within "spec"
 
Last edited:
Think about trying to thread a bolt into a threaded hole. If the oil on the bolt threads is too thick, it's not going to go into the hole with the bolt. Just like a truck that's too tall to go through a tunnel or underpass.
Yeah right. Just how big do you think oil molecules are?

It helps in these "thick vs. thin" discussions when people stick to physics.
 
In the US, CAFE. Honda seems to be only OE with tighter clearances - they were adamant the 1st gen Insight as well as the Civic Hybrid that followed up was to use only 0W-20, and they switched over to 5W-20 in the early 2000s before making 0W-20 standard. All Hondas, no matter where built are shipped with 0W-20 or 0W-16 from the factory.

The Euros are jumping on the thinner oil bandwagon as well. If you’re using start-stop, thinner oil gets to where it needs to go, sooner.
 
Which engine clearances are tighter? Clearance is still relative to bore size/bearing journal size and metal expansion with heat. I don't see clearances tighter than in the past. Probably with piston ring lands higher on the pistons in the last 20 years or so, there may be more piston ring end gap than in the past.


Clearances are in essence, the same as they have been in modern times. One would have to go back to the 1950's to find engines with bearing specifications outside of today's norms. People here may find it interesting that the Big Block Chevy used a standard main bearing clearance of 0.0013 inches, with a minimum rod bearing spec of 0.0009 inches! Although typical hot-rodder specs were about 2 thousandths for both.
 
Status
Not open for further replies.
Back
Top