ENGINE START UP&OIL PRESSURE

[Tom F&L GoR]

Hi Jamie,
Synthetics have no inherent wear performance advantage over mineral oils, wear is controlled by the additive system they use.

And yes, everyone has a memorable experience, good or bad, about synthetics or mineral oils, so let me show you one. This is from a fleet test, trying to extend drain intervals, comparing many additive systems and base oils. A high aromatic, "typical" mineral oil survived; synthetic oils didn't. The picture isn't doctored (except that the bottle is empty.)

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This engine (and one other) failed at 16,000 miles into the drain while the mineral oil went to 25,000 miles.

 

[Skip White]

I give up.......

 

[Steve 00RT/10]

Tom,

Thanks for the additive link. A guy could spend months in there.

Regarding ambient temperature and cold starts---we commonly see sub zero temps. I can remember years where we have gone over a month without getting above 0'F. My vehicles were always outside then. I mentioned chill factor, but really should have said the wind because wind it does have an impact on starting. Try starting a vehicle which stands with little or no wind at…. say -20F and one that stands at that same temp. with a 20-30 MPH wind cooling it down overnight. The one in the wind will turn over more slowly guaranteed. (assume 10W oils). Perhaps it's because w/o wind, the block never gets to -20 inside the engine compartment overnight. There is something to be said for real world testing. Because of the climate I live in, I have been able to take the same car with oil fills of each type in the same time frame and see how they perform in the extreme cold. There was no comparison when I did this..albeit 15-20 yrs. ago. The point being the viscosity ratings were the same. BTW--Amsoil does make a Series 3000 5W-30 diesel oil. Probably turn over a little better than your 15W. You should try it. hehe.

As for the European standards you reference----what I'm using meets them.

A couple questions/comments on additives. It appears that more is not always better when it comes to additives. It is very important that the package is properly formulated with the right amounts. Too much of any one additive can have a detrimental effect on oil performance and actually contribute to some of the things you're trying to prevent. ie sludge,foaming,corrosion, thermal stability. This then leads me to ask: If gasoline engine requirements are less and/or different from a diesel and therefore formulated for that purpose --why would one want to have all the other additives in there which diesels require, but not necessarily gas engines? Another question--Don't diesel oils have a higher sulphur content which promotes more wear?

An area we haven't got into is filtration. It is my understanding that synthetics are capable of holding much smaller particles in suspension(5 micron range). This means full flow regular oil filters due injustice to synthetic oil as they typically only filter to the 25-40 micron range. Most engine wear occurs in the 5-20 micron range. Filters designed with synthetics in mind will filter down to this critical size range. This filtration, which is able to take out these smaller particles, contributes to extended drain intervals. By pass filtration will filter to less than 1 micron. Air filters need to be efficient and kept clean as well.


As for changing oil frequently: I believe there is no reason to change any oil, much less a good synthetic, which meets the manufacturers spec at 1500 miles under normal driving conditions. The only exception I can think of would be the manufacturer recommending it, which I don't think you'll find anywhere for any highway driven car. I think a lot of Viper people get a little carried away with this. It certainly can't hurt to change that frequently, but it is definitely not necessary. Again one should always use a top line oil filter--not the $3 dollar variety.


Steve

 

[Skip White]

Once again Steve, well said........

 

[Tom F&L GoR]

Hi Steve & Jamie

Yes, it's neat that my day-to-day job applies to what I do for fun, also. And having these discussions with you guys that pay attention is pretty good, too. Ummm... what kind of grease do you use for reel mowers?

Steve, I do know that 15W-xx oils slow cranking speeds down. Most diesel oils also come in mineral 10W30, but it's difficult to find. No, I didn't know there was a 5W30 synthetic diesel (I knew of 0W-30s), that's cool! (pun intended.)

Yes, more additive is better, but it has to be formulated correctly. A diesel oil is formulated as a complete package, so all the extra goodies really are good and work together. In addition (another pun) the diesel oils run all the gasoline engine tests- and obvious pass- so they put the API SH or SJ claim on the bottle. They are not going to cause any problem. What worries the OEMs is when consumers use oil additives with crankcase oils; then "more" may be a problem because you can upset the balance and cause problems. Besides using the wrong types of additive (many oil additives still use obsolete gear oil chemistry) even more of the "right" chemistry may interfere or compete with the additives in the original oil.

Why would a diesel oil be better? Here's an example- you drive around, heat, fuel, and blowby find their way into the oil, create decomposition products and the oil starts getting darker. Dispersants in the oil (similar to dish detergents) keep these little nasties suspended in the oil so when you change the oil, the nasties are drained out. Diesel oils have to also contend with soot from the diesel combustion, so there is 2X or 3X the amount of dispersant - all more good stuff to help keep your gasoline engine cleaner. Further, diesel engines don't have precious metal catalysts, so there is no concern for the amount of phosphorus in the oil. The phosphorus is part of the anti-wear additive, which gasoline-only oils have a limit for (that will only continue to decrease.) That means diesel oils will have more anti-wear additive than gas-only oils. And the big deal for diesels is piston deposits - with life expectations of nearly a million miles, piston cleanliness is a prime concern. So diesel oils are formulated with roughly double the detergent level of passenger car engines.

Regarding the sulfur; I don't think sulfur in the oil causes any problems, I think it's the sulfur in the fuel. Fuel sulfur leads to piston skirt and ring land deposits, which leads to stuck rings, which leads to scuffing and wear - a typical long-term issue for over the road large engines.

Synthetics and any low-aromatic oils are not good solvents, which in one case is good. (This is bad when you can't dissolve the additives into the oil!) They tend to hold particulates in suspension well, and while I don't know about the particulate size, I have to go back to the dispersant additive; it's put in to keep any size particle floating (so it drains when you change your oil) and to keep particulates from agglomerating (forming bigger balls of abrasive materials.) I am no filter expert, but it makes sense to learn about filters and choose based on technical specs as well.

Oil drain intervals are like personal hygiene - I'll tell you what I do, but feel funny about telling you what to do. I target 3500 miles minimum, and feel fine if I can change it within the next 500 or so. Not only is that a huge cushion, having a 10 quart sump is another.