hyperbolical

Hello, just a quick question about coolant and trans fluid types and mixing them. I have an Advance Auto store not far away from me, so I've been using their FRAM green coolant premixed for my 98 xj. I recently had to replace alot of the coolant and didn't have a way to the store, so my brother picked up a bottle of the FRAM I just mentioned, plus a bottle of the concentrate to mix with distilled water. The only thing is, he picked up the FRAM Antifreeze and Coolant: Concentrate, Universal Extended Life all-vehicle version not the green version which was also available. This all-vehicle type is a more orangey or yellow color, and says "Universally works with all fluid colors; All OAT, POAT, HOAT & IAT." I questioned whether I should use it after I opened it and saw the color and read the label more carefully, so I erred on the safe side and used only the green pre-mixed along with another bottle I had opened previously, so no I didn't mix them. Question is whether I can/should use this other for top-ups or should give it to my brother for his own vehicles.

Similar question on transmission fluid. After some searching on the forum, most people are saying Dex/Merc not ATF. I recently had low transmission fluid and put in Valvoline MaxLife Multi-Vehicle red bottle - 1.5 quarts. It says "Suitable for 95% of traditional ATFs including Dex/Merc, Mercon LV & Mercon V". Should I have used it?

I have never changed or flushed my transmission fluid because my mechanic advised against it, but I am questioning that advice. (I believe I may have a transmission fluid leak somewhere - but that's another thread).

background: I bought this jeep in 2019, and it was previously owned by a state government, and had less than 100k miles on it. So I assumed it had undergone some kind of regular maintenance. Currently the tranny fluid looks brown. I had asked my mechanic to flush it but he said no. Now that he's retiring anyway, maybe I will do this myself if you all think it's a good idea. Can I just drain the fluid from the tranny drain plug and do a few drain and fills? I'm leary of cutting the hose as someone suggested because I'm afraid of creating more opportunities for leaks. The advice I read also said don't bother to replace the tranny filter, but what about cleaning out the tranny drain pan?

Thanks for any advice. I tend towards going with the original recommended fluids unless there are clear and good reasons for using new formulations. On the other hand, if there are no bad consequences from using new formulations, and they are cheaper/easier to get and possibly better for the vehicle, then I am ok with using them. I'm not terribly experienced with car maintenance and am learning. Have been taking the jeep to the mechanic for oil changes etc, and purchasing the fluids for him.

Rogue4x4

Generally I wouldn't recommend mixing coolants.

Dex/Merc only in the aw4. It doesn't like other fluids.

cruiser54

Green pre-mix and Dex/Merc as recommended above^^^

Just drain and fill on the trans fluid depending on its current condition. Got a pic?

hyperbolical

thanks, that's what I thought. I guess the Valv Maxlife is not really considered a true Dex/Merc. What about the roman numeral versions II, III etc? just go with basic? any brand you would recommend?
Here's a pic of the fluid as of today.

cruiser54

Dex III.

I would do a drain and fill now and drive it. Might need to do another one down the road.

Rogue4x4

PM sent

cpttuna

DEX Merc III on the trans fluid. Drain the Trans(you will get about 4 quarts) The drain nut I believe is 14 mm. Refill and drive about 100 miles. Drain and refill again. repeat as necessary until turns red again. I use Prestone for Antifreeze I buy the concentrate and mix with distilled for the overflow bottle.

hyperbolical

May I ask a stupid question, why do you say for the overflow bottle? I thought this was an open system, so you fill through the radiator cap and only on overheating does some go into overflow bottle?

cruiser54

fill through radiator cap.

Fill overflow bottle to the line on it.

lawsoncl

The coolant expands a bit when it warms up, and the extra volume pushes out into the bottle. When it cools, it'll draw it back in. If there is air in the system, it'll push the air out and draw coolant back in when it cools.

hyperbolical

Thanks for the explanation, it always helps me to remember if I know why! Every demonstration of flushing the xj cooling system that I saw on youtube only filled through the radiator cap and did nothing with the overflow. I guess the overflow bottle is considered 'optional' but 'recommended' lol. Or 'correct' but ignored by many. Anyway, I'll start doing it.