I always thought, and I could be wrong, that 5W30 (for example), means in cold weather (winter) it flows the same as a straight 5 weight oil and when hot it protects like a 30 weight oil.
One of my engines with billet crank,aluminum rods runs 0w20. Big block with 2.00” rod journals. I’ve been using Champion oil in that. Happy so far.
Yep. It's a good pimer. Aviation has a great deal of POL (petroleum, oil and lubricants), and the "operating range and conditions" makes for having to know a lot of stuff. We didn't simply pull into the nearest AeroZone, pop of the "710" cap and pour in what was on sale.
I think the nascar cup series racers, several years ago, used "0" grade oil in their qualifying engines.
The 6.2L Hellcat uses it, and plenty of those have been through the wringer. I don't recall the military spec but it says SRT on the Pennzoil labels:
I finished reading it, theres a lot of big words in there The word "shear" strength has me wondering, Im assuming it means the oils ability to support the crank, and cam off the bearings surface
Shear, in this context is oil's ability to withstand thinning or loss of viscosity in relation the the force of friction against the film/bearing ability. (oil film as a bearing surface, not the physical metal bearing).
I was going to say the exact same thing. Lots of cars are going to this.......andbits very very very thin coming out......scary thin
Yes, and these newer engines go 200,000 plus miles easily. They're daily driven, hot, cold, city, highway, I know engine management, more than 3 speed transmissions, help extend longevity, but the new oil chemistry must have an impact also..... thin as water, but strong. I don't believe the adage " these older engines need thicker oil" Were using updated bearing technology, roller cams and lifters, rockers that is IF your engine was rebuilt and updated. If you still run a flat tappet cam, you need ZDDP, not thick oil, its the chemical that provides protection, not the viscosity. I read somewhere its the presence of oil, not so much the pressure, pressure keeps the oil circulating. Maybe Im just bored and thinking too much
Oil is also an internal coolant. As long as there isn't metal-to-metal contact, the weight of the oil is less important. With tight clearance and sufficent oil pressure, you don't need as much HP to spin that thick oil.
Lots of things involved but I think the bearing clearances are the biggest thing. Modern bearings can be held to as tight as .0005" clearances which is very tight and requires great precision but that's good news for us since Buick specs are also tight so we could get into the range of .00075-.0010" and still be in spec for Buick. I've considered 0w40... in fact that might be what's in my 340 now and the oil pressure is still higher than it needs to be. When we went from straight 30w to 10w30 back in the 60's people thought it would wreck their bearings but that turned out fine. Jim
I run tight clearances with the Guy Fox mix of 2 qts 10/30 & 3 qts 20/50, only not synthetic....yet anyway. I do run synthetic in the Eaton Tru-Trac 410 rear though. Not planning any winter drives anymore.
Could be because the tight piston to bore and all other clearances plus cam specs & timing management allow oil to remain somewhat clean to 7,5k miles now. Less blow by and contamination going on.
