Has anyone successfully switched to low-weight synthetic on a high mileage engine?

all the isx's i've run. performed and sounded their best with mobile/delvac.

anything else and the motor just flat out sucked. lower fuel mileage, hotter temps, sounds like a tank. with delvac, they all purred like a kitten. ran cooler, and i average .5 mpg better.

 

Danny, I used to run synthetic blend in the winter just for the better cold cranking! And it makes a huge difference.

http://www.bobistheoilguy.com/motor-oil-103/


And thanks for the good info Cowpie!

 

I'll actually take that challenge. Not in -40 fahrenheit. That's ridiculously extreme. But I'm willing to devise some type of viscosity experiment at 0 F vs 180 f because I think it's all hogwash.

 

I like the "it's a myth" no fact guy and the "been proven by scientific research" fact guy.
I'll go with the proven scientific research guy. The days of "bill ran this in his engine and it worked great so I'll do the same" are way over.

 

-40F is not really all that extreme. Now if I was trying to make the case of -50F, -60F, or even -70F like we had to deal with occasionally in Alaska when I lived up there, that might not be a fair comparison. But many who drive thru Montana, N Dakota, etc have seen -40F in the winter months. And anyone who has driven in the northern tier of the country for most than a year has dealt with -20F or more. And the reasoning would be just as valid there. So I'll back off the -40F and go with the -20F.

There is some merit to the idea that some engines do tend to prefer a particular brand of oil. Engines tend to be like small caliber rifles. I can take two very well made, name brand .22 rifles and feed them the same good quality ammo. I will get different results. One will shoot better than the other. I can then try another good quality brand of ammo, and the results might swing the other direction. Nothing wrong with the rifles or the ammo. Just that one tends to shoot best with a particular brand of ammo. One of life's little mysteries. Engines and oils tend to be the same way. That is why it is a valid idea that if someone is getting mediocre results with one oil, switch to another the next go around and see if things improve. If Delvac gives you what you want, stick with that. If Rotella does right by you, then stick with it. I am not a brand oriented person. I look at results from the oil samples I send in. If what I was using wasn't giving the results I want, I would have no problem switching brands and even grades of oil the next time around and see how that works.

Unfortunately, marketing ads in slick magazines and promotions at truck shows and such can skew some folk's objectivity when it comes to oils. I especially get a chuckle when I see folks falling for the "one armed bandit" presentation of how great an oil or additive is. Check this out and see how Head and Shoulders shampoo will do a better job in your engine than the best name brand oil!

https://www.youtube.com/watch?v=q5WXbj5jbN8

 

One thing I forgot to mention regarding the cold flow thing. I cheat. Since my 1980's Alaska days, I have always installed oil pan heaters on my trucks and ag equipment. I have no problem using a 15w40 at -40F, or even -60F for that matter, simply because the oil is already 130F when I start the engine. I get fast oil flow to the top of the engine on the coldest of days. A block heater is great for the engine, but it does nothing for the oil in the pan. And oil pan heaters use very little wattage. About 500w. No excuse for someone with an APU, shore power, or some other form of power like a portable generator to not use an oil pan heater. Your engine will love you for using it. On days that are above 0F, an oil pan heater will take care of everything. The warmth from the oil will rise thru the lower block and help with engine starting. I rarely use the block heater until temps are below 0F. I just use the oil pan heater.

 

Against the strong advice of a friend of mine, who is a mechanic, I switched my 14L series 60 to full synthetic at about 500K. It used a gallon between changes on dino & I couldn't keep oil in it on synthetic. It was so bad that I dumped the synthetic and tried to go back to Delo 400. It still used oil like crazy. My mechanic friend told me it could take as long as 50,000 miles to get the rings re-seated. I never got to find out because Grandma made an illegal u-turn in front of me, so I took the insurance $ & upgraded to a better truck.

I really don't see the benefit to synthetic oil in a big truck unless you run in really extreme conditions. Regular oil, a bypass system & regular analysis will give you total operating expense equal or nearly equal to synthetic, I don't care what Kevin Rutherford says.

 

So because it didn't work once for you it won't work for anyone else ever?

 

I might not have even tried the Schaeffer blend I am using now, if it weren't for the fact that my engine just destroyed Delo 400LE 15w40 and the 5w40 synthetic versions. It was shearing the oil to a 30w in 15,000 miles. No probable cause. No fuel dilution. I went to the Schaeffer and the problem went away and the used oil samples were the best I had ever experienced. Would it have on Delvac? Maybe, maybe not. Is Delo a bad oil? Hardly. This all just supports my contention that engines, even within a particular brand and model, can have certain quirks that make them prefer a particular oil over another. That is why I told the OP that if he is getting decent results with the oil he is using, then stick with it.

Synthetics may or may not deliver on what they propose. Each engine is different. I have to admit, though, based on this Series 60 and on an ISX I had before, I am very sold on the synthetic blends. Gives the benefits of both worlds, while the cost is still reasonable. The additive package is more tailored to take advantage of both the base oils, which usually means it is a stronger add pack, which thereby benefits the engine.

It is truly a great thing that we have so many good oils to choose from. Sometimes finding the one that does the best job for you can be a PITA.