Tire and Rim size

[henry]

Now that we're on the topic of engines, does anyone run synthetic oil in their I6?

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If you do your own oil changes, I say do it.  There has been much debate on the website about this, and I'm a synthetic fan.  You do not need it here, but it does make starting easier (at least in my experience).  I only have a 2.5L in my Comanche, but the principle is the same.  I didn't run mine for one week last winter, thought it was plugged in but I forgot to turn on my outside plugs in my house.  It was the coldest week of the year, it started up (I don't think it liked it but it started anyway with immediate oil pressure).  On the other hand, the fleet I work for does not run synthetic, and the vehicles are never plugged in and we've really had no starting problems with that either, so its up to you.  

I wouldn't pay the $70 -$80 bucks a quick lube place charges for a synthetic oil change, but I change my own oil and I don't find it to be much more expensive.  I always look for Mobil1 on sale at Superstore or Ukrainian Tire and just hold onto it until I need it.

My two cents.

Darren :twisted:

[Bnine]

The old 4.2L six and the newer 4.0L six are indeed quite different beasts. I'd keep it at no more than 2500 rpms for sure.

More to do with carbs how tired they are then anything. A well setup 4.2 will still run along at 2500-3000rpm all day long, and will run up to 4k without a sputter.

Freinds 4.2 likes to run along at 2400 just fine.

A gear swap is more tedious then anything in my opinion because there is more time involved then anything. You opinion is different, thats fine.

Correct, its aerodynamics past 90k that effect the mileage more then anything. Not sure that was even needed. But simply put, thats why you usually get better mileage around town with jeep, then you do on the highway. Unless you stay 55 or under that is.

I've gotten the same average milage on my 03 with a lot of setups. 4.10's and 31's, 32's, 33's, 35's and 36's.

4.88's and 31's, 35's and 36's.

Sixes are pretty flat on mileage from the dozen or so I've owned in my time. And flat being not to hot no matter what you do.

Sure Red, take that picture, then let me know where to find that tranny with a 0.3:1 overdrive.

Thanks[/quote]