Question on synthetic fluids [Archive] - Forum


View Full Version : Question on synthetic fluids

10-11-2008, 07:58 PM
Hey all, I hope this hasn't been asked to death already (tried some searching already). I was wondering if it would be perfectly fine to run all synthetic fluids in my car. It's a 99 GT with 150k+ miles on it. I just use regular oil and I assume the Dexron ATF is in it still.

I'm looking to get some maintenance done on my car (tune up, tranny drain and fill w/ new filter, etc), and was wondering if there's anything 'special' I should have done. I don't need an oil change yet, but I'd happily dump Seafoam in the oil, get the change and filled with synthetic and a premium oil filter. I do know that the plugs need to be Delco Platinum, or shoudl I get a better type? My mechanic is great, he'll let me buy the stuff I want and he'll put it in, so I'm clear on getting what I want

I know we just got an 03 Durango with 50k miles and many of the suggestions I got was to flush the tranny and fill with synthetic ATF, get new synthetic oil in it, etc. I just don't know if my car will respond well, or if it's a waste of money.

gagt Mechanic
10-11-2008, 10:47 PM
If you have never done a trans flush be weary of doing one now. synthetic oil is fine but if you have oil leaks they will leak faster, synthetic oil will stay thinner longer, I would sug more of a high mileage. NGK makes great plugs also. is wires are oe sug them also.

10-11-2008, 11:34 PM
from what i understand, high mileage oils arent worth the extra money. stick with a regular oil or go synthetic. thats up to you. with that many miles it wont help wear anymore, but it COULD increase mileage in the long run. not saying it will 100%, but it could. be sure your useing a quality filter, not some POS house brand with synthetics. since they are thin, they get other particulates that regular oil wouldnt gather because of the "thickness" and the lower quality filters wont pick that up. a wix or even a fram is OK, not really worth going to get that k&n oil filter or the mobile one with that many miles. i run mobile one and a wix filter, with a k&n air filter and it runs like a champ with 100K on it. recently did the tranny flush, while he had the pan off i looked at it before he cleaned it up, no shavings on the magnet ( ask to see that before they clean it up). shifts great. starts smooth and runs even better. i used royal purple the first time i changed the oil. burned nearly a quart of that. after that i tried castrol syntec and it didnt burn a drop. same with the mobile one so far. my suggestion.. stick with regular oil. get new plus and wires, maybe consider coil packs and MAYBE the module as well. just keep it in good running order and youll do fine. like mechanic said, NGK makes great plugs, they have an iridium ( which is apperantly what these cars came with and should be replaced the same..) that is outstanding.i believe they are around 7 bucks a pop though. one more thing to do is get some MAF cleaner. clean those little resistors inside that thing. you would be surpised how much that can change how well your engine runs.

10-12-2008, 09:14 AM
^Do NOT get a fram filter! They are the worst filters out there. Use a quality filter like NAPA gold, Mobil1, or K&N, or even the stock A/C delco filters are pretty good compared to frams. On the topic of K&N air filters, they do have less air restriction but realize there is a trade off in filtration. They let more tiny dirt particles through than the stock filter element, so you will get more silicone in the oil and will increase engine wear over a long period of time. If all you care about is engine longevity and not HP, then stick with the stock filter. If you use a K&N filter, then using synthetic oil and a good oil filter are doubly important to reduce wear and get maximum life out of the oil before it needs to be changed.

As for the question of synthetics, there is no problem with switching to them at any time. It's better to do it early in the cars life, but you can use them whenever. That includes the trans. If the trans fluid has never been flushed though, I wouldn't have that done. I had that done on my grand prix I bought used at 127k miles, and 6 months later I was buying a new trans! Just have them drop the pan, drain it, and change the filter then refill with the new synthetic fluid. That will be sufficient. For plugs, Delco double platinum will work fine, or the new Delco iridium or NGK iridium are both good plugs. :thumbs:

10-12-2008, 10:09 AM
What Aaron said... although I'd skip synthetic ATF after the pan drop and just use Dexron VI. Since you're at 150k a conventional fluid would probably be better for you in the long run. That and its a hell of alot cheaper if your transmission decides to grenade down the road.

There's nothing like the feeling of having spent $100 on trans fluid only to have it ruined by a bad transmission.

10-12-2008, 10:10 AM
Thanks guys.
Yeah, I wasn't gonna do a flush cause of the high mileage. My mechanic did it on the Durango cuse I was switching from regular to synthetic ATF, and so he said it was better to flush out the old stuff instead of running a mix. With the GA, I'll just get the Dexron stuff to be safe. AS for oil, it seems like it won't matter much, so maybe I'll just get some higher grade reg oil. Any suggestions?

lol very true, Malaclypse

10-13-2008, 10:26 PM

10-13-2008, 11:18 PM
Mobil 1

Mike Jung
10-13-2008, 11:20 PM
German Castrol Syntec 0W-30 ;)

Mike Jung
10-13-2008, 11:21 PM
Pennzoil Platinum

10-14-2008, 07:59 AM
nice double post Mike lol

Thanks guys

10-14-2008, 07:47 PM
Castrol GTX if you want conventional.

10-14-2008, 07:58 PM
^^^ All I use is Castrol.. synthetic blend.