What is the current recommendation on synthetic engine oil?

[thinwater]

Rich,

dino

hasn't changed any over the years

Having spent the last 35 years in the lube industry I can tell you that this isn't remotely true. Even within base oil groups, oils change as blenders shift to different refiners and refining processes change. Group 2+ oils (used in nearly all products) have as much in common with synthetics as they do with Group 1 base oils of yore. Group 3 base oils are quite similar to synthetics.

You will also find that a great many "conventional" products use a portion of Group 3 or synthetics to insure they can stay in grade a high temperatures. Often these are referred to as correction fluids.

Group 3 oils are not synthetics in the sense that they are synthisized as PAOs. They are derived by severly hydrotreating dino oil. But they are called synthetics in the US (not Europe).

The most probable reason for a synthetic "causing" a leak has to do with seal swell. The less-pure Group 1 base oils caused seals to soften, swell, and wear more rapidly. When changing to synthetics, the seals may shrink back to proper (now worn) size and leak. "High mileage" blends generally contain seal swell agents intended to make the seals grow. This isn't good for the seals in the long run, but the engine will leak less.

If recycled oil is used in the blend (recycled bases stocks represent about 10% of the pool and they are used in more "virgin" oils than you realize, even factory fill) it contains synthetic oil. This is obvious. It is also one of the reasons that recycled oils have been getting better every year; more Group 3 and synthetic oil in the used oil pool. Also, because gas fracing has destroyed the historic markets for used oil (heating), much of the used oil is going into rerefined products now, a trend that is increasing. Close the loop tight enough, and about 30% of motor will be recycled. It is actually good stuff, but origins get lost in the blend market.

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I'm not saying you need to use synthetics. I'm saying the lines are a lot blurrier than you know.

 

[Rich Stidger]

Thanks thinwater, I appreciate your input.

 

[Rick D]

Thank you Thinwater. I am much more knowledgeable after reading your post! Not smarter, just more knowledgeable

 

[Rick Webb]

I've run synthetic oil in all my cars for the last thirty years even the used ones never had an issue with leaking nor heard first hand from anyone else who has had an issue after switching. The only issue I have had is the heater stopped working. The engines run much cooler and take much longer to get warm enough to get any heat out of the heater core. In fact my 65 Mustang would never get warm in the winter and I would have to put a piece of cardboard in front of the radiator with about a six inch hole cut out of the middle to get any heat inside the car.

For boats that only run the engine for about fifteen minutes each time they are started just getting in or out of the slip I'm not sure if that is a good thing or a bad thing.

 

[Gunni]

When I took the Diesel engine course at Mack Boring they were adamant about not using synthetic in my engine (which specifies regular motor oil) AND changing the oil mid season and before I put her up for the season. Mid season to refresh the additives and end of season to remove acids that attack the engine during a cold lay-over. Marine use is considered heavy load operation.

Regular Shell Rotella diesel oil is my choice and it has an interesting composition - when I get it on my clothes it leaves a wax-like stain that seldom if ever washes out. I suspect that wax coats the engine internals. My rule is that regular and more frequent oil changes are more important than the regular / synthetic debate.

 

[JamesG161]

Synthetics...
Full synthetic oils are derived from crude oil or byproducts through a chemical process rather than the distillation process used for conventional oil. The resulting synthetic oil has a more consistent molecular size and therefore tends to have somewhat more uniform properties.

Engine Oils...
Provide lubricity or viscosity. Viscosity goes down as temperature goes up. Obviously outside temperatures change for different part of the world (Cold to Hot range)

SAE Blends...
Maker of your engine provided the desired viscosity (SAE weight) as shown in Rich's first post ( my engine is same year and model as his)
If you look at his chart, 10W30 would be the best viscosity range for OUR recreational outside temperatures.

American Petroleum Institue (API) has made the standards for blending Oils to achieve the Range. 10 would be better in Cold and 40 would be better when hot.

CD CE CJ Rating...
They seem to be Fed requirements for air emissions reduction. Most likely the reason that synthetics are becoming popular to control "smoking and sulphur" to new lower limits of CJ. I am guessing that is also a way to recover used oil to make a synthetic.

This info was not in my "Data Base" and have done some web searching and local engine mechanic polling.

I switched, last 2 changes, to all synthetics, even in my 16 Hp Genset Yanmar.

Conclusion...
Rich with his distilled Oil and my Identical engine with Synthetics may be a good test case. My engine hours are 1280. I max cruise at 2100 rpm.

Obviously I (the SBO mad scientist) like the controlled spec Synthetic.

My (not to risky) bet is makes no engine wear difference.
Jim...

PS: I would love a 20W28 oil, which I can make by custom blends.

 

[Eddie7045]

One of the reasons that some new cars come with synthetics is that the newer 0W (zero) weights, such as 0W-20 weight, need to be synthetic in order to achieve the zero bottom figure so in order to use the proper weight of oil you have no choice but to use synthetic. As for the advantages of synthetics otherwise the main one is that they have a longer drain time. Changed at regular intervals wear protection is the same as conventional oil. If you are concerned with engine wear and longevity, change your oil more often. The problems that occur from going to synthetics from a straight weight oil, such as leakage and oil burning, are the same as changing to conventional multigrade. You should not, for instance, go from using straight 30 weight to 10W-30. The lower end 10W of the multigrade can leak past barriers that held 30 weight. The situation tends to happen with age as wear and hydroforming distort tolerances. In the past you could milk a little more life out of a tired engine by going the other way and changing to straight 30 after having used a multigrade oil initially. We then might later, before junking the thing, go a step further and add STP to increase the viscosity even more, the only instance I ever have or would ever add anything to crankcase oil. With the greater longevity and tighter tolerances of engines I've not seen that to be needed in over 40 years. In a boat or older car with an older engine I'd be on straight 30 weight if it were allowed in the manual.