Of course I use synthetic oil in my 1999 C230K, but wonder if there are any problems/drawbacks to switching to synthetic in my 1998 Jeep Grand Cherokee that just turned 81,000 miles. Thanks for any advice.

You may be in for some negative comments from some people.

I have done the switch on several high mileage vehicles, and have never had a problem doing so.

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2007 C 230 Sport.

A question on engine oil will generates 12345 different answers on this forum.
You asked if there would be any problem. My answer is no
You should also have asked if ther would be any benefits. I'd be consistant with my answer, unless it is a manufacturer's requirement.
jackD

The primary advantage of synthetic base motor oil is longer life due to the base stock's greater resistance to oxidation from time exposure to operating temperatures. Most OEMs who specify synthetic nowadays include an oil quality monitoring system that includes a sensor that measures the oil's dielectric strength, which is a primary measurment of oil quality. Oil is an insulator, but as it breaks down and becomes contaminated from engine operation its resistance decreases.

Without an oil monitoring system it's tough to know how much longer you can go between changes, but at three times the price you need to go two to three times longer between changes to make it economically efficient.

Beyond the longer life due to lower oxidation resistance, synthetics don't have any other significant advantages. They are not "more slippery", nor do they have a better additive package than any other API SL rated oil. They do have a couple of other advantages that are not applicable in too many cases, such as a lower pour point for better flow at arctic winter temperatures, and their higher oxidation resistance makes them a good candidate for applications that run excessive oil temps - like consistently over 250 degrees F.

Early blends have a reputation for causing older polymer seals to leak, but supposedly this has been corrected on current blends.

Bottom line IMO is to stick with conventional oil and follow Jeep's recommended change intervals - time or mileage, whichever occurs first.

Duke

Which engine? My wife runs a 95 ZJ 70 miles a day commuting. Its got 145K on it, been on Synth since 100k with intervals of 6000 miles. It uses a quart every 3k and is a typical 4.0, it leaks. (hell it leaked before the switch and still leaks ) Overall I'm happy with the switch, saves me having to change the oil monthly.




Joe

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Project Smoker, '87 603 powered wagon
Hauler, 96 CTD can you say torque?
Toy 73 Cougar xr7 convertible
Acme Automotive Inc.
Raleigh NC
919-881-0364

Depends on whether I feel "rich" that day or not... 88 4.0, no leaks.. 125K..

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89 300SEL Money Pit

92 Blown Buick Ultra Pimpmobile 220K and adding 1K per week

88 Wagoneer Slightly modified (Not for soccer moms)

04 Kia Sedona with every option... NICE