An auto tranny has more parasitic drag even with a locking torque converter? Not disagreeing. Just surprised and wanting to verify I understand you correctly.
If so, that's all the more reason to use synthetic auto-transmission fluid in an auto-tranny. I prefer Mobil One synthetic transmission fluid in my auto tranny (and in my 242 transfer case). The synthetic has made my transfer case much quieter and easier to shift.
If I had a manual transmission, I'd run synthetic gear oil in the manual tranny (and in the 231 transfer case).
I think synthetic oil is well worth it, and my preference is Mobil One.
Ironically, Mobil is a company that's mostly from your area (SE). In my area (NW) it's mostly Chevron, and to a lesser extent Union 76. I like Chevron products a lot, especially their conventional oils, but Mobil is also excellent for conventional oils, and for synthetics Mobil One is fantastic IMO, and Mobil One is well priced for synthetics and available almost everywhere (unlike exotic oils), even Walmart for many viscosities of motor oil and gear oil. Some of the auto stores here carry Mobil One auto transmission fluid (and of course motor oil and gear oil too).
If someone else prefers a different brand of synthetic oil, use what you prefer. Most brands of synthetic oil are better than conventional oil.
What seems to be missed is that even locked up, an automatic still has to pump fluid. The internals are heavier and larger, usually, than a standard (although admittedly shaped completely different). The pump exerts drag. The fluid being pumped through to operate the hydraulics and lubricate everything causes drag. At a minimum this is evidenced by heat generated by the system. Most of the heat from an automatic comes from the converter, but the rest of the transmission does make a fair amt. too. When I was (allegedly) running clutch and direct drive automatics in my past life, we were surprised at how much it took to cool them. On the topic of synthetics: Again, I run synthetic everything. It makes a lot of difference in just about every application. You know I run Mobil 1 motor oil. I have run quality products from all 3 of those companies. You are correct about Mobil being in this area. Chevron too. Shell, BP, Texaco, Ashland, and just about anyone else in th petro-chem industry. Right across the Mississippi River are two huge bottling plants. One owned by Exxon and the other by Castrol. What would surprise people is the number of brands bottled under contract there.
Generally speaking, it was always a rule in my mind that manuals are more efficient than automatics, but I'm sure that the newer ones are better (we certainly aren't dealing with new though).
It could also be that in stock trim the gearing combinations on the manual hit the sweet spot. They ran a taller rear end (3.15? Can't remember), and a shallower overdrive (0.79 vs. 0.75 in the auto).
I searched high and low for a manual for these reasons and the lower first gear, but they are pretty rare in later models. In the end I got used to lazy offroading with the auto, and kinda prefer them now.
I know this is not the answer for most of you but when I ordered a custom rebuilt 4.0L I had them put in a high torque cam. My mileage is now averaging 24 on the hwy at 65 mph. I have done no other mods. Might look at the high flow cat back.
I agree. There is much that can be done to improve the stock cam. The engines we have swapped cams in have made more power and been much more economical. There is a lot that can be done with the head and intake flow also. Combine the head work and the cam and you begin to have a serious engine. You guys with pre 2000 4.0s have it really good in regards to getting that dialed in and the OBD-I guys have it better than that.
Ya well, you suck in Winter cause you're comfy and I'm freezing my butt off in cold temps AND high humidity. It's often pouring ice cold rain, 30 to 70 mph wind, and 33 to 35F temp BEFORE wind chill. That is miserable. It actually feels a bit less cold when it gets slightly colder and starts snowing, because then at least I'm dry, and there is usually somewhat less wind when it snows than when it rains.
Most of the year here I'm miserably cold and it makes my joints hurt, and it's just as wet, or wetter, here than Louisiana. This is a COLD rain forest area, and near enough the Ocean and Mountains to get high winds funneling through the passes (where many of us live). I wear long underwear most of the year.
Now you can see why increasing my Jeep's engine temps helps my gas mileage, but in reality, I'm really only increasing my temps to approx what you're probably already running with a stock stat in your climate. With a stock stat I was running 185F to 190F in Winter, and that is to cold for efficiency. Winter is where I get my main benefits from my warmer stat, and some benefit in the colder half of Spring and Fall. I think I get some small benefit on cooler Summer days here. I doubt it makes any difference on hot Summer days (which we get few of here). When I say hot, I mean above 80F.
Misery is misery. To hot or to cold is hard on people. If you move, don't move here. My relatives from Texas come visit in July or August and complain about being cold while they're wearing their Winter coats. I don't think they could handle Winter here. I can barely handle Winter here. One of the worst parts of Winter here is few hours of "daylight" and that "daylight" is usually very dim due to heavy clouds. Often the street lights are on at noon and all afternoon for much of Fall, most of Winter, and some of Spring. It gets dark at 3:30 to 4 PM. The lack of day light can (literally) break people's sanity. I installed full spectrum lighting in my home and now I don't go as crazy in Winter as before. But I kid you not, between cold, rain, snow, wind, for 8 months, and very little sun for 5 months, it's a cold dark hell half the year here. Don't envy us.
Where is nice is somewhere midway between far North and Far South? That's where we should move. Northern CA in the West, or maybe Mason Dixon line in the East? Where should we move to Newtons? Like Goldilocks, I want someplace that's just right, not to cold or to hot.
Hmmm, how to reply to that without sounding rude. Well, I used to live in Minnesota where the winters were colder than Washington without the wet factor. And, the summers were not quite as bad as Louisiana but dang close. I have always preferred the winters as you can always put on more clothes to keep you warm where as in summer you can only take off so many layers. Otherwise the kids will laugh at me and the ladys will swoon.
One place to consider is San Diego. It doesn't have much humidity and the weather is fairly consistent from season to season. But, the only seasons are more wild fires or less.
Now comes to the rude part of my reply. I just moved to the mountains of Colorado. It can get to the mid 90's on occasion but it is usually high 70's to mid 80's. As for humidity, well, they do report it but 80% humidity here does not compare to 80% humidity back in Minnesota. And as for the winters, well, it can get below 0 but not often. And we do have all that lovely snow. But, (here is the rude part) DON'T move here. There are already too many people here. I mean I had to wait for the 4 cars to drive past my street before I was able to pull out.
But 3 of the 4 cars were jeeps, the other was a subie.
Okay, you people who drive jeeps can move here. And even a few of you subie and volvo drivers. But, no escalades. They are too big.
Thank you all for your informative, humourous and thought provoking comments. I am at work and a bit bored as there isn't much traffic here at the mountain and I have been reading this thread most of the day.
I'm at 18.4 combined city/highway and 21-22 highway over the last three weeks. My 97 XJ is a manual with a 3" lift and 31x10.5x15 Toyo Open Country A/T's. I have an UltraGauge calibrated via GPS.
Before I got the tires put on three weeks ago I had Goodyear Wrangler tires with terrible wear and a bad alignment. My mileage went up roughly 2.5 mpg despite going from a 235 to a 31. Now I'm thinking I will bring them back for 30's and see what happens.
My last XJ was also a 97 manual and got similar mileage without any modifications.
What are you considering southern climates? I live in NW AR. I am trying to get better milage out of my 06 unlimited and will try some of the things you mentioned, just woundering about the stat. Thanks
Bentonville, Arkansas! My Yankee neighbor. You guys see some pretty good heat in the summer, right? It kind of depends on where exactly you are hanging out. If you are driving where I've seen those triple digits up there, you might want to stay with the 195. If you stay in the altitudes and shadows of the cooler Ozarks, you could get away with the 205.
If your electric fan comes on often during on road driving (city or highway) in Summer with 195F stat, that clearly says do NOT put in a 205F stat.
If your electric fan occasionally comes on during on road (city or highway) driving in Summer, that says borderline climate. So I suggest try a 205F stat and find out how it affects your gas mileage in each season. My best guess is during Summer your city gas mileage will probably go down and highway gas mileage probably go up. The rest of the year (cooler seasons) I think your city and highway gas mileage will go up.
If your electric fan almost never comes on during on road (city or highway) driving in Summer, this is a clear sign to put in a 205F thermostat. Your city gas mileage will go up a little, and your highway mileage will go up a lot. This describes my climate and situation.
Another way to explain choosing a thermostat...
If your Summer days are frequently 90F+, use a stock Mopar 195F thermostat or a Gates 195F thermostat.
A Mopar 195F stat was tested by a JF member in pot of boiling water with thermometer and was found to open accurately at 195F. Other brands of (allegedly) 195F stats that were tested opened anywhere from 190F to 205F. None of the aftermarket stats that were tested opened at 195F.
Gates & ACDelco weren't tested by that JF member, but I know the 205F Gates is excellent because I'm using it. I'm also sure a 195F Gates would be excellent (if you need a 195F). I am confident the 205F ACDelco would be excellent because ACD is a stock/OEM stat (for GM cars).
The only brands of stats that I am confident will open at their rated temp are Mopar, Gates, and probably ACDelco.
When Summer days in the 80s, I don't think it matters which thermostat you have.
If your Summer days are typically below 80F, a 205F thermostat will be good for you. This describes my climate and the 205F Gates thermostat is working good for me.
If your Summer days are typically below 75F, a 205F thermostat will be great for you.
If your stat is an appropriate choice for your typical Summer days, it'll be good for the other seasons too.
IMO & IME
Warning: I often edit my posts a few times to get them complete, or to correct errors.
I would not go hotter,this motors run hot enough,u4 fan doesn't use much more power then running your lights and I wouldn't chance running a hotter stat,the hotter the motor the worse it runs and it wears faster