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Synthetic vs Conventional oil

YMMV, but every vehicle I have run synthetic in has had an improvement.
It does cost more, but at longer change intervals, you can break even or actually spend LESS. If you switch, I suggest some Amsoil full syn. Depending on the exact oil you get from them you can have intervals upto 25k/1year, with just filter changes. They now have a better premium oil with MORE ZDDP! which is great for our cast iron engines. I just purchased some from hodrodoil.com He is on this forum as well. Great guy!
 
I have read a few places not to run full synthetic in the jeeps. I didnt see why not until after I made about an hour drive on the highway running the jeep fairly hard. About 5 minutes after arriving at my destination I noticed a puddle of oil about 6 in across leaking from the rear main seal. Since then I have run mobile one standard oil and have had no leaking issues what so ever. I think that full synthetic is just to thin and the jeep 4.0 doesn't like it.
 
tjfritz325 said:
I have read a few places not to run full synthetic in the jeeps. I didnt see why not until after I made about an hour drive on the highway running the jeep fairly hard. About 5 minutes after arriving at my destination I noticed a puddle of oil about 6 in across leaking from the rear main seal. Since then I have run mobile one standard oil and have had no leaking issues what so ever. I think that full synthetic is just to thin and the jeep 4.0 doesn't like it.
Click to expand...
So are you saying that a pound of feathers weighs less than a pound of bricks?
Viscosity is what it is whether it be dyno, synthetic blend, or full synthetic. And you already had a leak, so the synthetic did not cause this.
And Mobil 1 is full synthetic. The Mobil company makes dyno oil as well though. Regardless of the engine, some higher mileage engines do not take well, or work just fine. So, know your facts before you go ranting about stuff that you do not know about.
 
if you have a small leak with conventional oil, it will be a bad leak with syn oil. Anyone who begs to differ can take up their argument with my garage floor. I've been told that once you go syn, you can't go back to regular. But then again, they told Columbus that the world was flat.
My 2000 pukes out Royal Purple much more freely than it did Castrol 10-30
 
After break in (or if its used right away) I run Amsoil synthetic in all my vehicles and parent's. I haven't had leaks to speak of after switching. I also do oil analysis and it seems the Jeeps like to get changed around 10,000 miles.

There is no reason not to run full synthetic in Jeeps. If there is a leak it will leak.. so fix it. Switching back to Dino oil because of a leak isn't actually fix anything.
 
Contamination of the oil is the main reason for oil changing. Mostly blowby of the rings is the main sorces there. Sin oil does NOT stand up any better to contamination then Dino will. For this reason I don't like the Idea of long interval between oil changes (25k miles) on old engine showing problems with blowby and any engine that is placed under heavy continues loads. Blowby always increases when loaded.
Sin oil will resist break down do to shearing of the oil molecules by stress/heat much better then Dino But this is seldom the reason most engines used in the normal mater need oil changes . ((((((((((((((((((((IMO))))))))))))))))
 
Thats the whole point of doing an oil analysis. To find when is the best time to change oil. Even then it will vary from engine to engine. And changing your oil at 3000 miles regardless of type is a complete waste.
 
There are MANY good reason for oil testing.
But just taking the cost into account. Could (I) a two jeep owner driving 20k max a year. Reasonably expect to recover the cost of testing by safely extending the oil change intervals? I like do it at 5K now with dino. Except when towing hot heavy and long. Then I run sin.
 
Testing your oil does not cost very much, and why not switch to Amsoil and run LONGER intervals? You can go up to 25k/1year
 
You might be able to go 25,000 miles on a single oil change, or less. What I have found on the 4.0L(and 4.7L V8 with 130,000 in it currently) engines is that they like 10,000 intervals. However it is pretty normal to see high iron content on the 4.0L UOA. Again, I have also seen an oil analysis from a postal use Jeep (stop and go all day) with a 25,000 change interval and it had a great analysis on the used oil, so your mileage will vary. The other engines I have done analysis is on the modern Jaguar V8. I've done it on two different engines. The N/A 4.0L likes 12-13k intervals(190,000 on it currently and it is a Nikasil engine), while the newer super charger 4.0L(120,000 on it currently)is up to 23,000 miles between changes and increasing.

Your mileage will vary due to use, environment, air filtration, etc.

Some of these engines have had synthetic since their first change when we purchased them new, some have has synthetic since 28k-100k miles. They have all received Amsoil and all can be considered high mileage. And we are hoping to get many more years of service.
 
My XJ have 266,000+ miles on the clock. Changed to all Amsoil at 140,000 miles. At first there were leaks from the rear main, the timing cover, the valve cover and the oil filter adaptor at the rate of .5 quart per 3,000 miles. I replaced the timing cover (vibration damper) seal. I do oil changes at 25,000 miles and filter changes at 5,000 +/- miles. Today, the 4.0 is leak free.

Oh, BTW I am using Amsoil in every thing since 140,000 miles except the D44 because of the ECTED and the need for friction modifier. That get regular dion juice.
 
techno1154 said:
Oh, BTW I am using Amsoil in every thing since 140,000 miles except the D44 because of the ECTED and the need for friction modifier. That get regular dion juice.
Click to expand...

I don't understand your logic of not using Amsoil because of a friction modifier.
 
Talyn said:
I don't understand your logic of not using Amsoil because of a friction modifier.
Click to expand...

At one time you could get the modifier as a addive and not just as a ready mix. This may clear thing up a bit.
But is the modifer compatible with Amsoil?
 
Calm down there johnny. I was only stating what I had read somewhere. I did not state whether it was fact or fiction. Just another thought. I was not ranting at all, did not say I was an expert, I was only passing on info I had read. If it was wrong, sorry!
 
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