Synthetic Oil

I have a 2007 Jeep Grand Cherokee Laredo 4x4. What would be the results, pro’s and con’s of changing from standard oil changes to a synthetic oil change? Should I make the change in this new of car? WIll gas mileage and/or power increase? WIll it make the engine run smoother, longer and with fewer repairs? Thanks for your help.

If the owner’s manual makes no mention of a requirement for synthetic oil, you won’t reap any benefits from making the switch except for possibly a slightly longer oil change interval, which would be counterbalanced by the increased cost of synthetic oil.

Just keep using what’s worked all along, and you’ll be fine.

Nothing special will happen; no increase in fuel mileage, no increase in power, car will not run any smoother, etc. If you change to synthetic, I would do it at the third oil change, so that the rings in the engine have had a good chance to seat.

You can lenghten the oil change interval somewhat after the warranty expires, but don’t double it! Synthetic oil has about the same amount of additives to combat deposits as regular oil, unless it is “EXTENDED DRAIN MOBIL 1”.

The major benefit of synthetic oil is easy starting in very cold weather, stability at very high outside temperatures (Arizona) and heavy engine loads (pulling a trailer), and increased engine life before overhauls.

On the downside, if you have a leak somewhere, synthetic oil is very thin and will leak more than regular oil. That’s why it is such a bad idea in an old car.

Do not exceed the drain interval stated in your owner’s manual, since it will void your warranty if you have a claim!

There is nothing magical about synthetic oil. If you switch to it you will not see any improvement in your Jeep’s performance nor would you detect any difference in mpg. If your owner’s manual recommends old-fashioned crude oil products, that’s all you really need. No harm in switching back and forth if you choose.

Mobil one, is the best stuff out there,and yes I use it.

and it does a GREAT job.

and yes the intervals are increased.(BIG TIME)




Whatever you decide to do, don’t drive without the correct levels of ZDDP in your Jeep. Nasty things might happen. Take a look a or google zddp to find out what’s happening. I know of one guy, who had the engine in his classic MGB reconditioned, and it failed due to low ZDDP levels! You may not need ZDDPlus if you have roller lifters in the engine (which you probably have) but it doesn’t hurt to find out anyway. Cheers from Downunder, New Zealand.

Whatever you decide to do, don’t drive without the correct levels of ZDDP in your Jeep. Nasty things might happen.

Yea and nasty things might happen if you do use it. I really don’t know much about the product, but I do know that if it were needed for your engine, it would be well known world wide. I sounds like mouse milk to me.


What apparently means to ignore crankwalk.

Crank, how do you know it is going a great job for you, and what is that great job that it is doing that other oils don’t?

I am not suggesting that Mobil 1 is bad, but I see no reason to claim it is better than any of a the other very good oils out there.

For me, the biggest benefit is oil getting to the engine on cold starts. It definitely gets up there faster, especially in cold weather, and since a lot of engine wear happens on startup, I am sure this is a big benefit. If I towed or otherwise challenged the cooling system, that would be important, too. I agree that only a slight extension of oil change intervals is desirable, and not beyond the ones required by the manufacturer. There are actually different kinds of “synthetic”, and I know Amsoil and Mobil 1 meet the best standard for a definition of the word. Amsoil costs too much. The cheapest way I know to get Mobil 1 is in 5 quart jugs at Wal-Mart.

In another forum dedicated to Nissan Trucks…There was a guy who switched ALL fluids over to synthetic…Oil, Tranny, differentials…He saw an overall gain in gas mileage of .5 mpg. At $5/gal it might be worth it.

I love this ZDDP thing. An article about cam failures in rebuilt PERFORMANCE engines using flat tappets appeared many years ago in Hot Rod magazine. Many reasons were listed. Bad Blocks with worn Tappet holders. Poor parts from a shrinking demand for Flat Tappets. Poor break in or a poor rebuild and, of course, ZDDP levels in newer oil formulations.

The key was the word “PERFORMANCE” were the pressure of the valve train to the lifter was MUCH HIGHER THAN STOCK. On stock engines, no problem was found.

All engine oils are “back engineered” to specks on older engines, including any with flat tappets.

This is how a rumor starts and the Aftermarket loves rumors. They can make a Buck or three on the resulting concerns.

A link about Oil Myths on Bob is the Oil Guy.

I don’t think that you will notice a significant change. Synthetic oil is a great product for fleet users. If used, it means longer intervals between changes. Mobil-1 even guarantees 15,000 miles between changes. That means a fleet owner can double the mileage between oil changes, saving down-time and reducing the motor pool staff. For the rest of us, it is probably not appropriate. It costs more than twice the price of regular motor oil, and you need a filter that will go 15,000 miles. Synthtic oil is great stuff and it won’t hurt you to use it - except a little in the wallet.

From what I have saves using wallyworld bottom grade oil, I could buy a new engine. In two years you won’t be in love with it any more and will go back to using the cheap stuff.

Um, Crank, perhaps you could enlighten us with your vast knowledge of automotive lubricants. Perhaps you could relieve us of our ignorance.

Agreement is universal that changing back and forth between dino and synthetic is perfectly okay as long as your owner’s manual doesn’t require synthetic. Some engines with turbos recommend it because of the high heat the oil is exposed to. Lab tests have shown it to be less susceptable to coking. Performance and mileage will be unaffected. www, has a good primer on oils.

As to whether synthetic is better, I’ve yet to see any real evidence (excepting the extreme conditions mentioned above). In a lab it can be shown to be superior in some respects, but there’s no empirical evidence that I’ve seen that it extends the life or reliability of an engine. In over 40 year of car ownership I’ve never worn an engine out, even after 338,000 miles. How can anything improve on that?

One suggestion. If you should switch to synthetic, I’d recommend staying with the same oil change schedule and not extending it. All engine oil, whether dino or synthetic, becomes conaminated and diluted by particulates and blowby, and the goal is to extend the life of the engine not to extend the life of the oil. Oil cannot be too fresh. Besides, there’s your warranty to consider.

Rely on mfg specs for oil recommendations.
Syn oil comes in grades.
V is, for example, Royal Purple.
IV is Mobile,example
III is Valvoline,example
Syn Blends are max 30 pct synthetic. Since none of the mfgr’s say, 15 percent.
Make sure your conventional oil is API M and recommended weight. M is most current.

A lot of misinformation here. Modern engines are so well sealed that the primary contaminate in oil is oil that has broken down. Contamination doesn’t come from the outside nor, with fuel injection, is there any significant “wash down”. There isn’t much blowby in a new engine either.

When I first started using synthetic oil in the late 80’s, regular oil would begin breaking down as low as 295?F. Synthetic oil is generally good to 450?. Oil in an engine can run over 300? during operation, and residual oil coating engine parts at shutdown will get quite a bit hotter. Todays regular oils can withstand a lot more heat, some approaching 400?.

Because synthetic can stand more heat, it breaks down slower, so it lasts longer. Because it breaks down slower, the filter also lasts longer so special filters are not needed. You do not want to exceed the manufacturers recommended oil change interval, especially during the warrantee period, you can use the maximum interval safely. For example, if the max interval is 7500 miles, you can do that with synthetic where you may only want to go 5000 miles on regular oil.

I have a Nissan PU that I switched over all the fluids to synthetic. I didn’t establish a baseline before the switch over so I can not confirm any .5 mpg gain. I was getting 25.5 mixed city/highway, it was EPA rated 20 city/25 highway.

Our new GM car specifies oil per GM4718M. Mobil 1 meets this spec. It is not a scam between GM and Mobil as others now meet the spec. According to the oil change computer, I anticipate oil life well over 10,000 miles. Break-in was not a problem; the engine uses no oil. If the oil life shakes out at around 12,000 miles and oil cost is 5 or so bucks per quart, then Mobil 1 will cost close to dino oil at 5000 mile oil changes at around $1.75 per quart. If you change at 3000 miles, then Mobil 1 or similar meeting GM4718M comes out ahead.

I have seen on the net that GM wants its engines to last at least 200,000 miles.

The 200,000 mile life is possible with almost any new engine provided it is maintained well. Today’s hotter running engines and all the underhood congestion calls for more stable oils. So synthetic is the right prescription. It would be good if the entire industry started specifying synthetic, then the increased average drain interval and larger additive package would allow car owners to more easily justify the cost of synthetic oil.

There’s no question that modern engines run a lot cleaner due to more precise parts and better materials and processes, and that more precise and leaner operation results in less washdown, and modern oil formulations withstand temperatures better, and those are the primary reasons cars last far longer and oil change intervals are typically 5,000 miles now rather than 3,000 miles…and engines now last 150,000 miles longer…even though engines now run some 20 to 30 degrees hotter than they did prior to about 1970. T-stats used to be typically 165 degrees.

However particulate contamination, blowby and washdown still exist as long as parts rub, rings have gaps opening and closing as they run, and surfaces are imperfect. Especially when engines get some mileage on them.

I still believe that these are true and legitimate reasons to not use synthetic oils to dramatically extend oil change intervals. I still believe that if the goal is to extend the life of the engine then the best approach is to use the better oils and maintain the same interval. And, actually, I’ve still yet to see evidence that (excepting extreme operating environments) synthetics extend the life of an engine. I’m still a believer that oils and filters can be too old, but not too fresh.

Rather than ther having been misinformation, I think we simply have a difference in philosophy on this issue.