I agree that synthetic oil is a better quality oil. I use it in my new car. But my concern is for higher mileage vehicle like my kj that has used dino oil all its life and consumes oil regularly that the synthetic will cause an expensive oil leak somewhere.

Chrysler 2.7 V6's have a chain/tensioner set-up like our 3.7's. The 2.7 is a time bomb, or at least they were before they were alledgedly "improved" a few years ago. Anyhoo, researching the death of my '00 2.7 in '04, many people had their 2.7's fail after switching to syn oil. For me, the engine lasted about 1,000 miles after I switched from Castrol dino oil to full syn at around 70K. There was nothing scientific about it, but my experiences & the things I read from others made me believe that the oil change had a bearing on my 2.7's failure.

Not to derail this thread even further, but from my own personal experiece my 2001 Sebring with the 2.7L does just fine when the oil changes are performed at regular 3000 mile intervals. I have, obviously, a long way to go on the car (only 50K miles) before I can say for sure that the Sludge can be avoided with proper care for your vehicle.

Yeah, you would think the reguler oil changes would prevent it, but you would be wrong.

People swear by the 3K interval despite it having been debunked as a tool of the dealerships & oil industry to sell more oil changes. But it is your money and your car, so do what you want. I am sure that changing it every 500 miles would be even better for you. I will follow the service pattern listed for my usage of my vehicle.

There are many anectdotal stories of higher mileage engines failing after switching to synthetic oil. Believe them or not, that it is up to you. That is why I included that the info was not scientific. But I would bet the title to my jeep that not all of those failure involved folks switching from an inferior or off-brand dino oil. The sludge issue is also not the only issue as many of the failures started as chain tensioner issues that caused catastrophic valvetrain damage that killed pistons, etc... immediately after a switch to syn oil and not lack of oil pressure due to what i can only assume people are assuming was caused by sludge blockages. Low oil pressure is indicated by a warning light. The light never came on until after failure in my and many other cases.

Best of luck on the 2.7 if it you ever decide to start driving it. j/k. But yeah, at 50K you are not yet in the mileage range of the issues. My advice, and take it for what it is worth, it to replace the chain & tensioners by 75K miles.

ICarl, engine failure is caused by any number of factors, with low oil levels only being one of them. Everything from poor design to mechanical failures to overheating kills engines. No, engine failure is not caused by one condition. But in your own statement where you say that only leaks/low oil levels cause engine failures, there are plenty of claims that syn. oil will be more apt to leak in high mileage engines than dino oil, creating what you say is the one reason engines fail. Please keep in mind that most of the claims about syn. oil's performance come from people wanting to sell you expensive syn. oil.

Most testing that i have seen indicates that regular changes with dino oil will provide the same protection. I don't know for sure either way as so much of each side seems to be propaganda and sales promos. If switching to syn. oil is a danger to engines unless you know 100% of its service history, why aren't the syn & "high detergent" oil folks saying " For God's sake, don't use our junk unless you know your oil was changed every 3,000 miles for the life of the car or it will kill your engine!!!"

A big caution for me on syn. oil claims is that ,except in a very few cases where they want owners to feel "special", the manufacturers do not require or suggest it. On initial install, they would pass the cost on to the buyer. The owners would pay for any increased cost in servicing the engine. So, if syn. oil was markedly better and would reduce the manufacturers' risks of warranty claims by its "suprior" performance, why aren't they using it/requiring its use when it would cost the manufacturer nothing to do so? Curious, huh?

The OP wanted opinions on the switch to syn oil on high mileage vehicles. I provided a cautionary tale from personal experience ( not internet rumor) and tied it to real world examples instead of " they say" or " you always hear" BS. Let the OP decide how much weight, if any, to give it.