Synthetic vs. regular disel oil

The oil film the engine requires is ONLY present after the engine is running.

A good case for a pre-lube system could be made.

ESp since one can be created at little cost , besides space aboard.

The reason some folks will use a quart of the same brand of Synthetic added to the stock oil is synthetic is claimed to have better sheer strength.

With a problem in the engine , like an overheat , the extra sheer ability might help the engine not freeze up.

Items driven with gears also like great sheer strength lubrication.

All insurance is a gamble ,with life insurance you bet you will die, the insurance co bets you wont.

The cost of a quart of Syn oil in the crankcase , like a gal of 2 stroke OB oil in the fuel is "insurance".

The cost is low , the savings perhaps great , and one does not need to drop dead to collect.

FF said:

............The reason some folks will use a quart of the same brand of Synthetic added to the stock oil is synthetic is claimed to have better sheer strength............

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I've never seen a recommendation by a boat or engine manufacturer or an oil company to mix two different types of oil in an engine.

Granted, if you change from one oil to another at oil change time there will be some mixing but after a few changes with the new product, the old will be pretty much all gone.

I would be worried about incompatibility of the oil or additives.

Ask Mobil Mixing Synthetic and Conventional Motor Oils

Ask Your Stickiest Question. . . Or ask us something you’ve always wanted to know about using our products. We’ll sort through all the submissions and present the best questions to our automotive experts. We'll share the questions and their answers here.
Question: Mixing Synthetic and Conventional Motor OilsCan you ever blend synthetic oils and conventional oils? If so, what is the ratio?-- Julie Patten, Des Moines, IAAnswer: Yes, synthetic oils can be blended with conventional oils. Several companies, including ExxonMobil, market synthetic blends which are a combination of synthetic and conventional oils. In the case of ExxonMobil, the ratio of synthetic to conventional oil in these products is considered proprietary information.

http://www.mobiloil.com/USA-English/MotorOil/Car_Care/AskMobil/Mixing_Synthetics_Conventionals.aspx

Of course you can buy commercial "blends". I'm talking about an end user creating his or her own blend without knowing about the compatibility of the oil or additives.

The quote above avoids answering that question.

Four Lethal Diesel Engine Oil Contaminants

L U B E T R A K . . . S o l u t i o n s R e s o u r c e s - K n o w l e d g e L i b r a r y

Here are some good resources. The second also has recommended threshold levels for a few engine makes.

rwidman said:

The quote above avoids answering that question.

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Don't ever hold your breath waiting for a lube oil company or an engine manufactuers to not avoid answering that type of question. They have lawyers to make sure their chemists and salesmen keep quiet about such things.

I doubt if your could even get them to state that air will or will not harm your engine.

The only possible problem I can think of re mixing is that the additives could be incompatible. Mechanics of yesterday used to say "never mix brands". I suspect it was an "old wives tale". And then there was the paraffin base oils that were different in some way from oils that came from another area.

For my cars in the summer I always mix 20-50W with 10-30W. I never use oils w more viscosity improvers like 15-40W. This all re dino oils only. Synthetic oils don't need VI improvers to achieve multi-vis ratings. For the extreme MV ratings I'm sure they do though.

Carl wrote;

"Is that a serious question?

The contact points would be bearing races, shafts, rings, cylinder walls etc., which as far as I know are not made out of marbles."

We used to joke that full flow filters were only good for "keeping out the marbles" Sorry.
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The key is using the SAME BRAND of oil to assure compatibility.

This is common on truck fleets where the desire is to switch to synthetic (no problems with storage on vehicles used 1000, 1500, 2000 miles a week. 6 MPG ,

1500 miles a week , even a 2% fuel burn improvement is Money in a year!

They will add a gallon when oil is needed , and monitor if the synthetic gets past the gaskets and seals.
One gallon at a time , till the changeover also helps load the oil filter more slowly.

RickB said:

Don't ever hold your breath waiting for a lube oil company or an engine manufactuers to not avoid answering that type of question. They have lawyers to make sure their chemists and salesmen keep quiet about such things.

I doubt if your could even get them to state that air will or will not harm your engine.

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True dat. I can't even get the SOS lab to tell me what normal wear on my engine looks like in terms of ppm of the various elements and compounds they measure. When I asked, they said it was "proprietary information." Which I translated to mean that if I had their reports and the oil analysis indicated no problems based on specific data but a problem occurred their lawyers thought they might be liable. Thanks a lot.

When I was an ultralight flier engine manufacturers and distributors would not recommend the use of synthetic oil in there engines. Here I sympathize w them though as synthetic oils (lubricants) varied too much. Dino oils are basically all the same as they all come from crude out of the ground but synthetics come from numerous base stocks not all the same at all and have different properties. It would be like endorsing wood .. one guy uses Oak or Ironbark and another uses Pine.

This is a good example of why, at times, it can be better to use a product or method not recommended by manufacturers or dealers. But you need to take the responsibilities associated w experimenters to gain the benefits.