Doing a 2018 jeep grand cherokee transmission fluid check is a bit of a different beast than it used to be on older SUVs where you could just pop the hood and pull a dipstick. If you've spent any time looking around your engine bay lately trying to find that familiar yellow or red handle, you've probably realized it just isn't there. Jeep, like a lot of other manufacturers lately, moved to a "sealed" transmission system for the 2018 model year, specifically for the ZF 8-speed automatic that most of these trims carry.
It's a bit of a polarizing move. On one hand, it's supposed to keep contaminants out and make the transmission "maintenance-free" for the life of the vehicle. On the other hand, if you're someone who likes to keep an eye on your own fluids or if you do a lot of heavy towing through the mountains, not having a dipstick feels a little like flying blind. But don't worry, you can still check it—you just have to get a little bit more hands-on.
Why the dipstick went missing
The 845RE or 8HP70 transmissions found in the 2018 Grand Cherokee are high-tech pieces of machinery. They're designed to be incredibly precise, and part of that precision involves having the exact right amount of fluid at a very specific temperature. Jeep (and ZF, the company that designed the transmission) figured that the average owner was more likely to accidentally introduce dirt into the system or overfill it than they were to actually help things by messing with the fluid.
That "sealed for life" claim is also a bit of a marketing term. If you talk to any transmission specialist, they'll tell you that "life" usually means the life of the factory warranty, not the 200,000 miles you're probably hoping to get out of your Jeep. If you're noticing weird shifts or you just hit the 60,000-mile mark, it's definitely time to figure out how to check that level.
Tools you'll need for the job
Since there's no dipstick, you're going to need to get under the vehicle. This isn't a "check it at the gas station" kind of task. You'll want to have a few things ready before you start: * A solid jack and four jack stands (the car must be perfectly level). * An 8mm Allen wrench or a hex bit socket. * A scan tool or an OBDII app that can read live transmission fluid temperature. * A drain pan (just in case). * Heavy-duty gloves, because the exhaust pipes sit right next to where you'll be working.
The "Must-Follow" temperature rule
Before you even touch a wrench, you have to understand that the fluid level in these 8-speeds is entirely dependent on temperature. You can't just check it cold, and you definitely can't check it when it's boiling hot after a long highway drive.
The sweet spot for a 2018 jeep grand cherokee transmission fluid check is usually between 86°F and 122°F (30°C to 50°C). If the fluid is too cold, it hasn't expanded enough, and you'll end up overfilling it. If it's too hot, it's expanded too much, and you'll think it's full when it's actually a quart low. This is why having a scan tool to read the internal sensor is so important.
The step-by-step process
First, you've got to get the Jeep up in the air. This is the most annoying part of the process because, as I mentioned, the car has to be level. If you just jack up the front, the fluid will all rush to the back of the pan, and your reading will be completely wrong. Use jack stands on all four corners and use a spirit level on the frame or the transmission pan itself to make sure it's flat.
Start the engine and let it idle. You want to cycle through the gears—Park, Reverse, Neutral, Drive—holding each one for about five seconds to make sure the fluid is pumping through all the internal valves and the torque converter. Put it back in Park and leave the engine running. Never pull the fill plug with the engine off, or you're going to get a face full of expensive transmission fluid. The pump needs to be running to keep the fluid held up in the internal components.
Now, crawl under there (carefully!) and find the fill plug. It's located on the passenger side of the transmission case, toward the rear. It's a bit tucked away, and like I said earlier, the exhaust is right there, so watch your knuckles.
Using your 8mm hex, slowly loosen the fill plug. If fluid starts to trickle out immediately, you're likely at the correct level. If it's a steady stream, it might be slightly overfilled. If nothing comes out at all, the level is low. The goal is to have a very thin, tiny thread of fluid just barely weeping out of the hole when the temperature is in that 86°F–122°F window.
What should the fluid look like?
While you're under there, take a second to actually look at the fluid that's weeping out. Mopar 8&9 Speed fluid (which is what these Jeeps use) is usually a clearish-green or a very light straw color. It's not the bright cherry red you might be used to from older vehicles.
If the fluid looks black or dark brown and smells like a piece of burnt toast, that's a bad sign. It means the fluid has broken down from heat or friction, and simply "checking" it isn't enough—you're likely looking at a full fluid and filter swap. On these 2018 models, the filter is actually built into the plastic oil pan, so you have to replace the whole pan to get a fresh filter. It's a bit of a spendy job, but it's cheaper than a new transmission.
When should you actually worry?
If your Jeep is driving perfectly, you probably don't need to do this check every weekend. However, keep an eye out for "the signs." If you notice the transmission hunting for gears, or if there's a distinct "clunk" when you're coming to a stop, the fluid level is the first thing to check.
Leaks are another big one. The transmission pan on the 2018 Grand Cherokee is plastic, and while it's tough, it can warp over time or develop leaks around the gasket. Also, the electrical connector (the bulkhead plug) on the back of the transmission is a known spot for slow seeps. If you see red or green spots on your driveway, don't wait—get under there and check it.
A quick word on the "Fluid for Life" myth
I can't stress this enough: ignore the manual if it says you never need to change the fluid. ZF, the people who actually built the transmission, recommends a fluid service every 50,000 to 70,000 miles depending on how hard you drive. Jeep just wants to keep the "cost of ownership" numbers low for the first few years. If you plan on keeping your Grand Cherokee until the wheels fall off, treat that transmission fluid like you treat your engine oil—check it, change it, and don't believe the "sealed forever" hype.
It's definitely a more involved process than it used to be, and honestly, it's a bit of a mess if you aren't prepared. But taking the time to do a proper 2018 jeep grand cherokee transmission fluid check can save you thousands of dollars down the road. If you aren't comfortable getting the car level on stands or messin' with fill plugs while the exhaust is hot, any decent independent shop can do this for you in about 30 minutes. Just make sure they know the temperature requirements, because that's the part most people get wrong.