The following is from a lubetips e-mail distributin I am on
( http://www.lube-tips.com/ )
I thought you guys my find it interesting...


Q & A
Switch to Synthetics?
"I am considering replacing the mineral oil in my engine with a synthetic oil. The engine has 50,000 miles on it. I have heard that the mineral oil and synthetic oil are compatible. Is this true?"

Generally, the reference to synthetic oil for an engine, means a lubricant is formulated with a polyalphaolefin (PAO) base oil. PAO, which is often called synthesized hydrocarbon, is pure and is compatible with mineral base oils.

However, because the PAO base oil does not dissolve additives effectively, it is usually formulated with an ester co-base (usually di-ester and/or polyol ester). The additives are soluble with the ester and the ester is soluble with the PAO.

Likewise, the PAO tends to cause seal shrinkage and the ester causes seal swelling, so the effects are offset when both base oils are present. It is the ester that can cause problems when one changes from mineral to synthetic. Ester base oil used alongside PAO base oil in lubricant formulation has excellent natural detergency. In other words, it will clean up varnish on component surfaces as a result of thermal and oxidative degradation of the lubricant. When one switches from a typical mineral-based engine oil to a typical synthetic-based oil, the varnish layer will be removed by the ester in the synthetic oil and become suspended.

This suspended material can rapidly clog filters and can block oil flow passageways and lead to component starvation. The same is true for gearboxes and other industrial machines. So think twice about switching to synthetic oils in applications where the engine or other machine has been operating for some time with mineral oils. If you decide to make the switch, try to clean the system before making the change, then monitor it carefully once you start it up.

Drew Troyer, Noria Corporation

 

Good info Brian, as always.

 

"When one switches from a typical mineral-based engine oil to a typical synthetic-based oil, the varnish layer will be removed by the ester in the synthetic oil and become suspended. "

Just wondering: If the ester stuff is so good at removing varnish, why is it not an additive in dino oils for the purpose of preventing varnish buildup?

 

I'll bet the argument of petroleum based v. synthetic v. synthetic blends could go on forever. I have a '99 V10, and was getting top end rattle on very cold morning start-ups, which was driving me nuts. I switched to a synthetic blend (Schaeffers, although I'm not endorsing it) and the noise stopped immediately. I swear I could feel the difference under acceleration. I also have my oil analized to monitor wear. Right now I'm running 12% of normal wear - that's on iron content, and less on all other readings. Bottom line, that makes me happy, but I'd probably be as happy with any brand that gave that result. I'm sure, though, that I'll stay with the synthetic blends. An interesting side note too, is that after you establish a "pattern" of wear, your lab will likely recommed an oil change interval. You can save money with extended intervals, which can offset the extra cost of the oils.

 

Brian, that's interesting technical information and thank you for posting it.

However, their conclusions and theory fail where the rubber meets the road. I have never heard of or personally know anyone that has had an engine fail because they switched to a synthetic in a high mileage engine and it "plugged up" in the manner described.

No authoratative technical source or automotive magazine, not Consumer Reports, none of the vehicle manufacturers, nobody has discussed vehicles that have actually been damaged by switching to a modern formulation of synthetic oil.

No one here or on any of the other on-line auto or truck sites has ever mentioned an engine failure due to a switch of oil types.

If using a motor oil that slowly removes internal deposits and crud can damage an engine by "rapidly plugging up filters and oil passages", why wouldn't that happen when people use products and strong solvents specifically formulated to quickly remove internal engine deposits--The engine flushes, products like Rislone, Marvel Mystery Oil, BG Engine Purge, Quick Clean, etc?

I myself switched to Mobil 1 in a '96 F-250 that had 129,000 miles on it when I bought it, and I have experienced no problems after a year of hard use. The truck runs like a dream.

Could, should and might aren't the reality of it, not in the real world. There are so many old wive's tales still circulating about synthetic lubricants that it's unbelieveable. Reality: It doesn't happen.


Best,

Bill

---------------------------------

2002 F-250 S/Cab Short Bed PSD 4x4. SCMT +80 HP, AFE Magnum intake.
1996 F-250 S/Cab Long Bed 460. E4OD auto, 4.10 posi, Air-Lift suspension, K&N filter in modified intake box, modified ignition advance curve, Edelbrock 2x61 mm throttle body, L&L 4 into 1 headers, milled heads, 3" exhaust system, cat & Flowmaster 70, modified MAF meter. 7,700 lbs GVW, 5,700 lbs empty.
{E\...F}

 

The key is flushing the engine prior to installing synthetic. I've switched to synthetics on high mileage engines, but flushed them with a solvent prior to doing so. No problems.

 

When I switched to the synthetic blend I was warned only that an oil analysis would be of no use (after the first change of synthetic) because of the cleaning properties. Seems to give a bad analysis with all the "dirt" floating around. Never heard of deposits causing engine failure. As far as flushing goes, I really get nervous about the strong detergants in some flushes. What I use is a quart of ATF. It has amazing cleaning properties, but is still an oil, so can't harm the engine. If you've ever had a sticking lifter, try ATF. I'll bet it stops it, as it always has for me. And to prove it to yourself, get your hands all greased up, then "wash" them in ATF. You'll be amazed.
Frank