2002 Chevrolet Trailblazer i6 4.2L

[mrdctaylor]

Guys,

My parents are giving my daughter their old 2002 Trailblazer (4.2L i6) to my daughter. It has about 130K miles. They've never done anything but change the oil, so I plan to service the transmission and drain/fill the coolant. As far as oil, though, I'm not sure what to do. I use Pennzoil Platinum 10W30 in both of my current vehicles. My dad has always used 10W30 conventional (usually Pennzoil or Castrol I think). Is there any reason I should/shouldn't switch to synthetic? I like the idea of using synthetic on this vehicle too since my daughter will be going off to college and I don't want her to have to fool with getting oil changes during the semester. I just don't want to introduce any potential problems by putting synthetic in a 12 year old vehicle. I realize that this may be an old way of thinking, so I guess I'm just looking for advice. My #1 goal is to NOT cause issues while at the same time giving this car good protection. Thanks!

 

[SwampSurvivor]

You won't have any issues by switching. Only thing that may happen is it may clean up a leak or two that is currently plugged by sludge / deposits.

What about spark plugs?

 

[mrdctaylor]

Good question. My dad mentioned he'd had it "tuned up" when I asked him what he'd done to it besides change the oil, but I don't know when that was. That's worth checking on--thanks.

 

[i812]

Any thoughts on changing brake fluid as well as the rear diff?

 

[MolaKule]

Originally Posted By: i812
Any thoughts on changing brake fluid as well as the rear diff?


Yep, change ALL fluids and check for leaks.

My daughter has a later model version of the TB and the front diffy had a left axle bearing leak.

Remove the rock shield and check for leaks around the oil filter as well. The oil drain plug may need replacing as well.

Spark Plugs should be replaced if you are not sure when they have been replaced.

Recommend XW30 as well, possibly 5W30 or 10W30 HM.

Other than that, they are pretty tough birds.

 

[i812]

The 4.2 L I6 Atlas LL8 appeared on the Ward's 10 Best Engines list from 2002–2005. Sounds like a solid powerplant! Take good care of it.

 

[mrdctaylor]

Good call on the differential too. Does anyone know if the 2002s have a drain plug on it? I know that some later ones do not. The owner's manual actually doesn't say to drain/fill it...ever! It just says check the level and top off as needed.

 

[matrass]

Originally Posted By: mrdctaylor
Good call on the differential too. Does anyone know if the 2002s have a drain plug on it? I know that some later ones do not. The owner's manual actually doesn't say to drain/fill it...ever! It just says check the level and top off as needed.



I have a 2002 and mine has a drain plug on it. first time I changed it I removed the cover and cleaned it all out. after that I just used the drain plug and the fill hole. I would suggest changing the thermostat and doing a transmission fluid flush thorough the cooler lines along with dropping the transmission pan and filter. cleaning out the throttle body would be a good idea too. I love my 2002 btw and plan on running it as long as I can. like everybody else said , do the plugs and other fluids. do not forget to check the air filter as it is easy to take a look at .

 

[mrdctaylor]

Interesting. The manual states that the diff gear oil must be 75w90 and meet the GM 9986115 spec. M1's gear oil doesn't meet it. :-(

 

[gomes512]

Yeah did not see that spec on Mobil 1 gear oil, unless I missed it. Nonetheless, I've been running it in our '03 anyways. 64K so far using 75w-90 with summer boat towing, no issues to report. Change intervals are 30K.

 

[95busa]

My wife had an 02 LTZ. I ran trop-art syn blend 5w30 in it, changed the transfer case oil with GM stuff (blue, crazy expensive, forgot what it was). I threw a new air filter and a fuel filter on it and she ran great with almost 100K on her. Great truck, minnesota winters were slowly eating her up (rad core support looked ROUGH).

 

[abycat]

Check brake pads too

 

[NHGUY]

They love to have valve timing solenoid valve issues.

 

[Rand]

I'm pretty sure that GM 9986115 is just calling for a Full Synthetic 75w90 and its not very strict.

I wouldnt worry about the gear oil not meeting it as long as you use a Full Synthetic major brand gear oil.

This was basically GM's attempt to make you buy 30$/qt gear oil

 

[Nick1994]

My grandma has an 02' Trailblazer LTZ. What a great car! It's been 100% reliable it's whole life and has 99k miles. If it has a weird tick on startup, not to worry that's just GM piston slap. Nothing to worry about. I've run Castrol GTX in it a few times and now has Chevron Supreme HM in it from my stash. This thing is a tank and doesn't care what you throw at it. I hangs the oil every August, which happens to always be every 4,000 miles for my grandparents Lol.

Only issue it has had is a crazy vibration sitting at a stop light. This was the motor mounts. Good luck!

With my grandparents driving it, it gets 17-18 in the city and I got 22 mpg on the highway at 80 mph in the hills! No doubt it could do even better!

 

[artificialist]

Ignore the proprietary GM gear oil specification. I have serviced many of them using M1 or Valvoline Synpower 75w90 without a single problem. If this truck has 4WD, be sure to have the transfer case fluid replaced, and check specifications carefully. Some take gear oil, some take Dexron III automatic transmission fluid, and some take something called "GM Auto Trak II" which has no equivalent. The front differential would probably use the same oil as the rear differential.

Usually GM trucks of that size have an oil life monitor, and when it is time to change the oil, a warning will appear on the instrument cluster. If you teach your daughter to simply heed that warning, and then take her car to a repair shop for an oil change, there should be no problem. The factory oil life monitor is calibrated for conventional SL engine oil, and comes on only when needed. That prevents your daughter from having to worry about oil changes.

I recommending removing the transmission pan to change the fluid, because usually there is garbage sitting on the bottom of the pan, and flush machines don't remove it. I highly recommend buying an OEM transmission pan gasket because they are far longer lasting. For the transmission filter, OEM and premium aftermarket filters are best.

 

[mrdctaylor]

Ok, so a couple more questions:

1) What type of oil do most of you that have this car run in this engine? Conventional? Synthetic? I don't mind spending a little extra for synthetic. But like I said, I'm just concerned about causing leaks. My dad always changed the oil every 3-4000 miles with conventional. That seems like overkill, so I'm *thinking* this should be a clean engine internally. My daughter will be going off to college and I don't want her to have to worry about maintaining it. I'd like to run it out a lot longer.

2) Does anyone know how much coolant will drain out if I just drain the radiator and don't do a complete flush?

Thanks!

 

[ChrisD46]

Your engine I believe takes 7 qrts. of oil and a nice happy medium would be Quaker State Ultimate Durability 5W30 (buy two jugs at WM) which will safely run for 7500 mile intervals ...A number of owners using good quality synthetic (meets DEXOS 1) report going 10,000 miles or 12 months - which ever comes first . The radiator holds approx. 12 qrts if memory is correct . This can be a little tricky as you don't want any air bubbles in your hoses from the drain plus having to deal with used anti freeze coolant disposal .

 

[KCJeep]

I just don't see any I-6 "needing" a full synthetic. If you want to use it by all means do so but I imagine it'd run well over 300k on Quaker State or some such thing.

 

[mrdctaylor]

12 quarts just for the radiator? Or is that for the whole cooling system? I've got a couple of other cars and their rads both hold less than 2 gallons (8 qts).