Novak Conversions Jeep Wrangler JK radiators

Synthetic oil

Boogieman

Boogieman

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Joined
Aug 22, 2025
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Location
Pismo Beach, Ca
I have read non synthetic oil is better for the 3.6 engine to guard against dry starts. Just purchased a 2015 JK with 70,000 miles and need to do an oil change. Appreciate advise on the subject. Currently engine runs great, no ticks, just smooth quiet idle. Hope to keep it that way.
 
I'm not really sure it's better for cold starts, but they do say you can get better mileage from using it. I like to add a little Lucas Oil Additive to my oil so that it makes it kinda sticky.
 
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WSS said:
Whew, glad he is not the one with the red TJ.

The TJ forum was a blast. I miss my TJ.
Click to expand...

I still have mine, after tomorrow it will be on Jack stands in the shop getting a spring transplant.

Taking out the old RC's and installing the new Rockjock's

Taking the TJ to Coalmont OHV tomorrow for the last ride on the RC's.
 
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Back in 1990, I spec'd out a Peterbilt truck for the company I was working for. Something I will never forget, was on the diffs, Peterbilt would offer literally DOUBLE the mile warranty if we took delivery with synthetic fluid in the diffs. another story was a earthmover co that I work with did Caterpillar's local dealer network for "SOS", or scheduled oil samples in all their equipment, diffs, planetaries, engines, trans, etc. They found from the SOS comparison that Synthetic fluid (especially engines) would gain 20-30% life in hours. So a $40k engine would go 12500hrs instead of 10000hrs, etc.. I always use synthetic in my entire fleet. I have for 20+ years. Forklifts, flatbeds delivery trucks, personal vehicles, etc.. The only vehicle I do not run any synthetic in is my son's Tesla. I even use synthetic grease when possible.

Just a personal testimony here.
 
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WSS said:
Back in 1990, I spec'd out a Peterbilt truck for the company I was working for. Something I will never forget, was on the diffs, Peterbilt would offer literally DOUBLE the mile warranty if we took delivery with synthetic fluid in the diffs. another story was a earthmover co that I work with did Caterpillar's local dealer network for "SOS", or scheduled oil samples in all their equipment, diffs, planetaries, engines, trans, etc. They found from the SOS comparison that Synthetic fluid (especially engines) would gain 20-30% life in hours. So a $40k engine would go 12500hrs instead of 10000hrs, etc.. I always use synthetic in my entire fleet. I have for 20+ years. Forklifts, flatbeds delivery trucks, personal vehicles, etc.. The only vehicle I do not run any synthetic in is my son's Tesla. I even use synthetic grease when possible.

Just a personal testimony here.
Click to expand...

This is good intel . I use Mobil 1 synthetic in my 2008 JK . 305 000 KM / 189 518 miles . Runs really good .
Am interested in your thoughts .
I was under the impression from what I have read in the past non synthetic differential
fluid is the way to go . As it sticks to gears better than synthetic . Is this info
inaccurate or out of date ?
 
Syn's are said to flow better on starts, especially in cold weather. Id like to hear the theory on the dino is better. That being said, pretty straight forward, keep it changed and use good oil and you cant go wrong. Check out PQIA for oil additive packs and tests if your bored.
 
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Synthetic has been shown to be better in pretty much any application. The only exception I can think of would be a old school engine. Machining tolerances were looser, and the thicker oil can help keep drips to a minimum.
Take a look at what manufacturers are doing. Full synthetics. Including Jeep. If it's good enough for a million dollar hypercar...
Personally, I use Mobile One Extended Performance in everything. Change it every 20,000 miles or annually.
 
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Novak Conversions Jeep Wrangler JK radiators
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