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Switch to synthetic oil or not?

32K views 108 replies 56 participants last post by  Majnoon 
#1 ·
Just did the first oil change since getting my 97 Wrangler. I was considering switching to Mobil 1 Synthetic since it was on sale, but ended up staying with standard. Anyone recommend or not recommend this? Btw theres around 78k on the engine.
 
#40 ·
Its possible!!!

I gotta hit the hay. Been a rough month. In laws came back and are sleeping in my bed. I havent had a decent night sleep in a month, and I try to keep working out. On the up side I gotta see my boy get " Athlete of the year" pretty cool. Later man
 
#41 ·
is there any way to tell what kind of oil I have? synthetic or dino?

the guy I got mine from lost his job (seaplane pilot - long story) just after the jeep got on island. he had no money to anything with/to it. it was driven about 15 miles a week just to keep everything "working". he had no idea the type of oil used and unfortunately there are absolutely no service records. what's a poor boy to do?

next week the 60K service and complete fluid flush is scheduled. I really don't to mess anything up and end up trashing my engine.
 
#42 ·
Don't worry about what oil is in there now, synthetic and conventional are completely interchangeable (mixable too) and you can switch back & forth without any problems whatsoever. There are way too many false rumors concerning synthetic vs. conventional that get repeated until they seem like the gospel.

You know what you get when you mix a 5W-20 Synthetic with a 10W-30 motor oil? A 7.5W-25 Blend that would work just fine. :)
 
#43 ·
Im glad you said this Jerry. I have thought for years that you couldn't switch from synthetic back to conventional. Now that I've actually looked into the matter you are completely right... As always :worthy:
 
#44 ·
Of course you can switch back and forth from conventional to synthetic. Companies produce synthetic blends which many people use. Those are literally synthetic oil blended with conventional oil. If you can put both in the car at the same time, you can definitely interchange them.

And just my .02, but if you are using synthetic oil and still changing your oil every 3500 or 5000 miles, then there is no reason for you to not use conventional oil in the first place.
 
#45 ·
I was actually just discussing this earlier in another thread but i dont judge oil changes by mileage. I judge it by when the oil gets dirty. Unless the vehicle is sitting alot and then i will change the oil at 6 months to keep everything running smoothly
 
#49 ·
Just a personal opinion.

The reason why I change my oil is to remove impurities from the motor like fuel and moister to name a few. It was my understanding the reason why synthetic oils last so long is because it keeps its synthetic state by not mixing with impurities where a conventional oil will absorb and mix with unused fuel and moister in the crank case and drain out with the oil during an oil change. I was an ASE Certified Automotive Master Tech and its surprising how little I know about lubricants. I did work for and was a mechanic for Fedex, 16 years. Fedex used conventional oil we got 250,000 miles out of our gas vehicles with 5k oil changes. If there was any value in synthetic oil I'm sure Fedex would have used it?

One time back in the 80's I was in a motor that supposedly the owner always used synthetic oil? The oil looked great, but the inside of the valve covers were coated with a gooey oily substance, maybe the impurities that should have drained out with the oil, who knows?

Use a good oil, filter, and change it often and you will be fine.

I am thinking about changing the front and rear diff fluids with a synthetic on my 2014 Unlimited, but conventional oil everywhere else.

Rob
 
#50 ·
Just a personal opinion.

The reason why I change my oil is to remove impurities from the motor like fuel and moister to name a few. It was my understanding the reason why synthetic oils last so long is because it keeps its synthetic state by not mixing with impurities where a conventional oil will absorb and mix with unused fuel and moister in the crank case and drain out with the oil during an oil change.
Not so much an opinion as possible facts lol just facts that I have never heard. Is that really the reason why synth lasts longer? I thought that it just took longer to breakdown and therefore was able to stay clean and good for longer?
 
#58 ·
It only stands to reason that there are different wear and heat, patterns between lubricated parts when different lubricants are used. Just plain water is the best lubricant there is but if you use it, and then go to oil or synth, problems arise. Go figure! :-(
 
#59 ·
Synthetic is the way to go. Jerry is right about conventional oils being better than ever. But in my experience synthetic is better. It does not break done as fast. It handles heat better and the viscosity is superior. Can you put 300,000 on your engine with conventional oil? Of course you can. Regular maintenance and treating your engine right goes a long way. All my vehicles deserve synthetic and that's what they get.
 
#60 ·
If you decide to switch to synthetic at that mileage, make sure you do the following BEFORE the switch:

change oil pan gasket
change valve cover gasket
change rear main seal

I changed mine to synthetic (1999 TJ 2.5) at 82k and ALL of those started leaking before the next oil change was due. Bleh.......

It doesn't run any better or worse, it doesn't have any more or less power, it smells the same, and still does not fix itself so I think it's not worth switching.
 
#62 ·
Who eats sliced bread? Yuck lol jk
I'm not so much worried about temperature as I am about how clean it gets and keeps the engine. I know that in the past my jeep has not always been taken very good care of. When I got the jeep (from my own parents none the less) and changed the oil for the first time there was a significant amount of sludiness to the ink black oil. :puke: Poor Jeepie

Edit: this was a while ago and everything has been running pretty smoothly since but after that first change I've been worried about what the inside of this engine might look like
 
#64 ·
The filter can't tell the difference between synthetic and conventional oil. The Purolator PureOne oil filter will be fine.

Folks, there is not a significant difference between synthetic and conventional lubricants, it's not like they aren't essentially the same thing. :)
 
#66 ·
Hey Jerry I heard some bad news about Purolater Filters but not sure which ones. Something about how the filter material deteriorates or something. I can't remember exactly but was recent. You know anything about it? I always ran Purolator Classic filters until I read the news about them not being as great as they used to be. I know it's a little off topic but....
 
#65 ·
Correct me if I am wrong, but I've always heard that the type of driving one does has a lot to do with engine longevity. Vehicles that get up to full operating temp and stay there for a while tend to last longer than ones that cover short distances, idle a lot in traffic, etc. In the second scenario synthetic oil and frequent changes might be more of a necessity.
 
#67 ·
The main reason I don't use Mobil One is because I only put 2,000 miles/year on my TJ, meaning one oil change per year....I'd be wasting a lot of money dumping Mobil One out of the engine after only 2,000 miles.

Besides, the 4.0L engine is so well designed and manufactured, and is so under-stressed compared to the more high performance engine types (say for example Chevy's LS6 engine or my 5.7L Hemi in my GC) , that synthetic oil is really not necessary to achieve very long and reliable engine life.

.......but to each his own.
 
#68 ·
I do not think synthetics are the end all and be all of oils. If you are doing a short change interval, 3,000 miles, then a good, quality, name brand conventional or semi-syn oil is fine. If you are running 5,000 to 7,500 or more on a cycle then I would want a synthetic.

That said, I have been using Mobil 1 synthetic products since they came out back about 79 and I have accumulated significant mileage on several vehicles with it and as well I have been privy to some oil testing back long ago. I would be comfortable with any name brand product, conventional or synthetic, just consider your use and change intervals and you will be fine.

J
 
#69 ·
If you are changing your oil at less than 7,500 miles, there is no reason to buy synthetic. It's just a waste. I mean whatever floats your boat, but if you're changing at 3,000 miles you are simply changing too often. The manual of your jeep lists that basically unless you're driving in a desert every day at 90+ degrees and going on constantly short trips, you should change your oil at 7,500 miles. And that is with conventional oil.

The 3,000 mile oil change is a myth invented to make you waste money. If you want to know when to change your oil, check your manual. Don't pay attention to what the jiffy lube station says. They just want you to keep coming back...
 
#71 ·
His "opinion" is based on fact and I agree with him as I am in the trade. Like he said go read your manual or goto school and learn about oil lubrication and delivery systems and how they work, and when you come back with a Diploma saying you know more then the average person on that subject then you will see what we are talking about ;).

Who you going to believe? The loser at Jiffy Lube making $12 an hour that gives two shits about you or your car and just wants your service back ASAP because it makes his boss happier. Or are you going to believe the Engineers and Lawyers with thousands of dollars invested in education and the years of experience. That would not mislead you due to lawsuits. I think they know what they at talking about when they write manuals and service intervals ;)
 
#75 ·
I was in the trade also, I do not work at Jiffy Lube, I make a whole lot more than $12.00 an hour but thanks for the insult. I have several degrees including Masters and plus 30 and I am an A&P and a master mechanic. A little of my handy work awaiting completion of the airframe (by me also), IO360, custom fuel injection, mostly built from Superior PMA parts and painted Viper yellow, also by me:



Not everybody here is a teenager, just starting out, I have already finished most of my careers and as I said, I will stay with exactly what I said in my initial post in this thread. I accept you have an opinion, I have stated mine and will stay with it.

J
 
#77 ·
Even Jeep is trying to say change oil every 3000 in my manual..... yet the service manual says 6000 miles for conv. oil.... go figure. I knew an GM engineer who agreed.... every 3000 miles was wasting money, it just gave the service department more opportunities to find something needing repair. My manual.... has a lot of THINGS NEEDING DONE that isnt in the service manual i have.
 
#79 ·
I use valvoline full synthetic in my 05' TJ. I Chang the oil every 10-12 thousand miles which usually ends up about 2-3 x a year. My jeeps oil always stays at the full mark on the dipstick so it burns no oil, and I drive the crap out of it here in the arizona desert 100 mile round trip to work 6 days a week. I think that if you use a full synthetic oil and drive your car almost every day for over 30 min at a time you will be fine changing the oil every 6-10 thousand miles.
 
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