2nd Synth Oil change

Pote · **Posted:** Sat Jan 19, 2008 3:24 pm

So I've done my second consecutive synth oil change (I'm now at 68-69K) and I have to say my KJ is now running smoother than ever - and it was darn smooth to begin with, like a top! It actually idles a full 100 rpms less than it did above and beyone the 100 rpm drop when I installed the FIPK intake. It now idles right at 500 rpms. After the K&N intake it dropped from about 650-700 rpms down to an even 600 at idle. now its right at 500 rpms and strong.

Driving at highway speeds, it is also about 100-150 rpms less than prior to the second oil change. (I didn't see this change after the first oil change of synth but is noticable after the second)

At 63-65 I am cruising at exactly 2000 rpms. At optimal driving speed (for me is 61 mph when it just slips into 5th) I'm now cruising at 1900-1950 rpms. Before the FIPK and the 2 synth oil change, I was running at about 2200+/- rpms at that speed.

Anyhow, I'm amazed at how well the synth (Mobile One) has taken to the KJ. It really is worth the extra cash and I'll be using it for the life of the KJ. The engine seems quieter, more responsive, and has more pepp. This all in freezing temps here in Cleveland with boat loads of snow....I can't wait to see the benefit during the summer months. I'm also still consistently getting 21-22 MPG....I anticipate that will go up another 1 mpg in the warm months again.

I highly recommend the Mobil One synthetics.

Jeep4me99 · **Posted:** Sat Jan 19, 2008 3:27 pm

thats pretty good results. i think i'm gonna switch to full syn now. put in a synthetic blend last time in prep for the full syn switch.

saxdogg · **Joined:** Fri Jun 02, 2006 7:26 pm **Posts:** 199

I don't see how synthetic oil would make your rpm's drop, especially when in gear! Your motor will turn a certain rpm based on the gearing and speed...yes?

Jeep4me99 · **Posted:** Sat Jan 19, 2008 3:54 pm

saxdogg wrote:

I don't see how synthetic oil would make your rpm's drop, especially when in gear! Your motor will turn a certain rpm based on the gearing and speed...yes?

i'm sure there are differences in the viscosity. as the oil heats up and get worked, synthetic doesn't get as "thick", resulting in less impedence for the moving parts.

Guest · **Posted:** Sat Jan 19, 2008 6:31 pm

yes, but when the converter is locked up at freeway speeds, the rpm's wont change. Maybe he wasn't seeing lockup on the converter before?

isutherl · **Posted:** Sat Jan 19, 2008 6:47 pm

I have seen that a lot of guys run synthetic. Does anyone have problems with leaks or gaskets failing, especially the 02 and 03 with higher mileage? I don't think I would ever run synthetic in a suv or truck, but maybe I don't know what all the benefits of running synthetic are, I just seems that its much more expensive.

Guest · **Posted:** Sat Jan 19, 2008 6:49 pm

running mobil 1 in my 3.7, nothin leaks but the pinion seal on my front diff.

Also...I change my oil every 5k, FWIW

USPLibby · **Joined:** Thu Jul 28, 2005 12:29 am **Posts:** 377

I've been running Mobil 1 synth since about 4500. I'm at 100k+ with no complaints or problems. The 3.7l seems to really like synthetic oils, it runs a lot smoother at idle. I noticed some engine "shimmy" at idle with regular oil.

I also change my oil every 5k.

JJsTJ · **Posted:** Sat Jan 19, 2008 8:17 pm

Imagine if you were running an actual Full synthetic oil like Amsoil or had Full synthetics in everything. :wink:

Both my KJ's and my 185,000 mile, 14 yr old XJ run all Full syn lubes and no leaks, no problems. My XJ had a rear main seal leak when I bought it but I fixed that, filled it up w/ Amsoil and it has been fine ever since, no other gasket on it has been touched since I have owned it. The additives in syns are even better for seals and gaskets so leaks are not usually a problem unless it is on a much older vehicle that was leak prone anyway.
Tha benefits to running full synthetics has been known for many years and FWIW, Amsoil was the originator for automotive use in 1972 w/ Mobil chasing behind 2 years later and offering No improvement over Amsoil. It has been proven since 72 and they are still following in Amsoils footsteps.

Sure it costs a little more to buy Amsoil initially but if you take advantage of even a double the normal mileage change interval or so it pays for itself. It is also an easy way to save doing a couple services a year and it is better for the environment too w/ less waste oil and filters over the life of a vehicle.

jeepkj02 · **Posted:** Sat Jan 19, 2008 8:23 pm

I always run a full synthetic in my KJ. Wouldn't even think of running dino oil. I am running dino in my axles now, and it haunts me everyday... :shock:

Synthetic gear oil is REALLY expensive..like 12 bucks a quart!

DarbyWalters · **Posted:** Sat Jan 19, 2008 8:29 pm

There are really no downsides to running synthetics these days...the extended service offsets the higher initial costs and the reduced wear and better fuel mileage are a plus.

JJsTJ · **Posted:** Sat Jan 19, 2008 8:31 pm

jeepkj02 wrote:

I always run a full synthetic in my KJ. Wouldn't even think of running dino oil. I am running dino in my axles now, and it haunts me everyday... :shock:

Synthetic gear oil is REALLY expensive..like 12 bucks a quart!

Under $15 a Qt (My Amsoil pricing for 4 qts Severe Gear to your door w/ tax & shipping) for something you don't have to change very often is a bargain for the peace of mind you get from knowing you are running the best. We spend tons of money on our Jeeps buying them the best of other products but then think that spending a little more on the best lubes (pretty important ones at that) is not neccessary or too costly. Huh?

Sorry but my vehicles deserve the best lube and filtration products available and regardless of being a dealer, my Jeeps will get the best just like they did before I became a dealer.

Pote · **Posted:** Sat Jan 19, 2008 9:08 pm

saxdogg wrote:

I don't see how synthetic oil would make your rpm's drop, especially when in gear! Your motor will turn a certain rpm based on the gearing and speed...yes?

I don't know either, but it just became really noticable directly after the second oil change. Maybe coincidence and nothing more....but it's consistently running smoother with less rpms being used. I'm not one to fight such a good thing. LOL

saxdogg · **Joined:** Fri Jun 02, 2006 7:26 pm **Posts:** 199

whichever the case...i'm all for smoother idle!

...my cold start idle seems rough as hell right now!

Rush345 · **Posted:** Sun Jan 20, 2008 12:59 am

First You may experience some oil leaks with a good syntheic this is due to the High detergent features of a quality synthetic. If all that keeping it from leaking is crud that has built up and after cleaning leaks then it's just showing problems in a dirty engine :shock:

as to Change in RPM's with a synthetic being so slick the engine will experience less drag and increase RPM's the computer will learns and readjust less drag= a smoother running engine and better performance and fuel economy :twisted:

Erievon · **Posted:** Sun Jan 20, 2008 3:21 pm

Jeep4me99 wrote:

thats pretty good results. i think i'm gonna switch to full syn now. put in a synthetic blend last time in prep for the full syn switch.

Not the first time I've heard of this theory, but I've never heard people's reasoning as to why they feel the need for this intermediate step? Is there data that states the need to ween your motor off dyno oil?

I've switched countless motors over from Dyno to straight synth with no adverse effects. I'm not looking to flame, just wondering if I'm missing something.

Jeep4me99 · **Posted:** Sun Jan 20, 2008 3:48 pm

Erievon wrote:

Jeep4me99 wrote:

thats pretty good results. i think i'm gonna switch to full syn now. put in a synthetic blend last time in prep for the full syn switch.

Not the first time I've heard of this theory, but I've never heard people's reasoning as to why they feel the need for this intermediate step? Is there data that states the need to ween your motor off dyno oil?

I've switched countless motors over from Dyno to straight synth with no adverse effects. I'm not looking to flame, just wondering if I'm missing something.

no real theory behind it for me. i plan on going to amsoil and not sure if going straight from dino to syn would mean i would have to change the amsoil earlier, due to some dino still being in there. (ie, change at 3k instead of 15k).

Erievon · **Posted:** Sun Jan 20, 2008 3:53 pm

Ah, now that I can buy, a cleansing step so when you put the expensive stuff in there it's a little less "Contaminated." With Amsoil's extended drain intervals I can see where you'd want it to be a little cleaner before you start with that.

KJ4ME · **Posted:** Sun Jan 20, 2008 4:34 pm

its amazing what some motor oil can do isnt it?
i use pennzoil platinum full synthetic and i have the same results, lower RPM's, slightly improved fuel economy, and faster warm up time along with the engine being quieter and smoother. as ive stated before the only thing that sux is my dealer dosen't stock pennzoil so its $18 tacked onto the $29.95, and since they have to acquire the oil, i cant just take it in i have to schedule everything, but well worth it!

KeighJeigh · **Posted:** Mon Jan 21, 2008 12:59 am

Jeep4me99 wrote:

Erievon wrote:

Jeep4me99 wrote:

thats pretty good results. i think i'm gonna switch to full syn now. put in a synthetic blend last time in prep for the full syn switch.

Not the first time I've heard of this theory, but I've never heard people's reasoning as to why they feel the need for this intermediate step? Is there data that states the need to ween your motor off dyno oil?

I've switched countless motors over from Dyno to straight synth with no adverse effects. I'm not looking to flame, just wondering if I'm missing something.

no real theory behind it for me. i plan on going to amsoil and not sure if going straight from dino to syn would mean i would have to change the amsoil earlier, due to some dino still being in there. (ie, change at 3k instead of 15k).

When I change over, I'm not going to worry about partly because I intend to change my oil more often than the maximum allowable. I think the amount of dino that is left in the overall mix is so minuscule it won't matter in combination with the fact that it is completely dispersed. Here is what Amsoil says on their FAQ page:

Quote:

Are AMSOIL Synthetic Motor Oils and petroleum motor oils compatible?

AMSOIL synthetic motor oils are fully compatible with all petroleum motor oils, and there is no danger in mixing the two. Mixing AMSOIL and petroleum oil, however, is not a recommended as a general practice. Performance and long drain intervals will be sacrificed and the oil should be promptly changed, at maximum, within the next 3,000 miles.

and then this:

Quote:

Is there a recommended procedure for changing to AMSOIL Motor Oils?

There are no special requirements; however, in older vehicles or those with high mileage, it may be advisable to use AMSOIL Engine Flush first. This will ensure that the engine is clean and free of any accumulated contaminants which might have an effect on the service life of AMSOIL Motor Oils. In all cases, it is good judgement to install a new AMSOIL Absolute Efficiency Oil Filter (EaO) every time you change oil.

2nd Synth Oil change

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