Yes, molecule size is a well known fact. However, consistency is where the key lies in that fact. Having the molecules be perfectly sized is what allows manufacturers to run very close bearing and cylinder wall clearances and small oil jet passageways without having to worry about lubrication issues. You can guarantee that due to molecule size, the specified clearances will always allow the safe minimum to be present to protect from metal to metal contact, something you can’t guarantee when using conventional oils and varying sizes of molecules with the same tightly specified clearance.

Also, saying that you would not want diesel oil in your gas engine is RIGHT, not wrong. Base oil itself is not what the problem is, but the additive packages used in the oils are CRITICAL in your engines survival. Gas engines have a very different additive package requirement then Diesel engines do, and much of it has to do with operational heat ranges, pressures exerted on internal parts, and surface speed of various internal parts. By using diesel oil in your gas engine, you are depriving it of many much needed additives that would otherwise help protect and extend the life of your engine. These additives also break down over time due to contamination within the oil (condensation, blow by, etc), and will react with these contaminants to turn acidic. This is the real reason you want to perform oil changes. The filters do an excellent job of keeping oil free of large particles, but due to the loss of all important additives, the only way to reintroduce them into the oil is to simply change your oil.

 

 

BTW, the not using diesel oil in a gas engine was also agreed with by the WS6 owner Valvoline employee.

 

What?

 

A guy local to me who works for Valvoline and owns a WS6 told me that using Diesel oil in a gas engine wasn't a good idea.

 

Well it works for me for hundreds of thousands of miles and also in my turbo car.

 

No. 10-30 oil is recommended, not 10-30 synthetic. 10-30 was developed for gas milage requirements. Manufactures must meet the CAFE requirements. Perhaps, engine manufacturers had to tighten bearing tolerances for the use of thinner oils to hold pressure. I do not know, I do know it increases milage.

Also, you should do your homework before making assertions. Diesel oil has every additive plus others not contained in motor oil. Go to the manufactures spec sheets. It is usually higher in zinc and phosphorus. It almost always has a higher TBN number, and is heavy with detergents, anti acid additives, water dispersants, anti rust additives, and maintains better viscosity at higher temps. The oil stands up to a pounding in heavy duty equipment, and has high levels of anti foam additives to do so. Something desirable in 8000 RPM FI builds or circuit and oval race cars.

Finally, and at the risk of repeating myself, I will restate that you can use diesel oil in a gasoline engine but you cannot use motor oil in a diesel. Think about that. That means the protection offered by motor oil is inadequate. Diesel offers the same protection as motor oil and then some. Think about it when you say diesel oil doesn't offer the same protection as motor oil. BTW, for those who prefer to use 30 weight oils, diesel oil comes in straight and 10-30 grades, as well as the standard 15-40.

 

Stock/bolt-on motor...any full synthetic 5w30 or 40 will do. Aggressive heads/cam setup.... Castrol Edge 5w50 or mobil1 15w50 depending on the lifters used. Fwiw there was a guy who ran 20w50 synthetic VR1 in a stock LS1 and the engine oil analysis results showed less wear then 5w30. The caveat is that it will cost a little fuel mileage and power. The only reason why OEM's use thin oil is for economy and better efficiency.

 

http://www.bestsyntheticoilfilter.co...complete-list/ Here is a good list of oil PSI ratings

 

 

Yeah. The only one I would consider on that list is #21, VR1. Nice zinc and phosphorus levels along with some moly. Most of the oils post N/A under those categories, and that says it all. They could sell you dirt, if it had a little GL-5 additive.

 

This^. In a perfect world, the crank would turn on an oil film and there would be no wear because no metal touches. But, the oil picks up air, not just by sucking in air when the pick up is uncovered. Oil flies around the crankcase in a storm, hitting the crankshaft and other moving parts. The air is then trapped in the oil. This is called oil entrainment. Most of the bubbles are molecular in size. Antifoaming additives cannot prevent it all. Cavitation occurs in the oil pump and galleries, especially the lifter galleries.

When those molecular air gaps are trapped between the crank and bearings, metal to metal contact occurs. To stop metal wear, zinc and phosphorus are added. There are other additives, but they are the work horse of the industry, and are used because they are effective and cheap. The zinc acts as a sacrificial metal. It wears away instead of the bearing materials. It is then replaced by fresh zinc contained in the oil. It is a constant process of sacrificing and replacing zinc, and occurs repeatedly in a nano second.

The reason zinc and phosphorus levels were reduced is due to a government mandate to protect catalytic converters. These mandates went into effect in 2007 for cars and in 2017 for trucks, which are also required now to use converters. So, zinc levels were dropped to about .008 instead of 0014. The oil manufactures quit posting zinc and phosphorus levels after 2007. If you look at their spec sheets, available on their websites, the stats are from 2007. The same is true of diesel oil after 2017. We are told that they engineered the oil to be just as good against wear, but they will not post whats in it. Yeah sure.

The auto manufacturers are happy to replace fewer cats during the 100k warranty period. They are not responsible for the car after that. I post here in the Gen III forum because I have a Gen III car (04 GTO). The original specs called for 10-30 SL. SL has about .0014 zinc content. Now its asserted that is no longer necessary. What it really means is that the levels were dropped to meet the mandate.

The most useless of the new API grades are the SMs. At least the newer SNs have more anti foam additives, which cut down air entrainment. But of course SNs were developed for use in VVT motors, which are used to increase milage. Not for wear, milage. Milage is not a bad thing, just realize SNs were introduced for milage and not to fight wear.

Finally, late model BMW high performance models recommend 10-60 oils. So, why would they recommend such oil in such a tight clearance car? BMW makes its recommendation based on necessity and not milage. Their cars all suffer from the guzzler tax, while GM, Ford, and Chrysler all try to make their 700 HP cars get 29 MPGs in sixth and use light oil to avoid the tax. The reason bearings last with todays oils is due more to better bearing materials, design, and manufacturing techniques and not because of the oil.

I hope this helps. I am not trying to antagonize any forum members, but instead would like for you to think about.