Motor Oil is Killing our Cars / LONG / OT - Page 10

jadcock · #**136** (**permalink**) 05-03-07, 06:32 AM

Quote:

Originally Posted by Playdrv4me

If theres one thing I see we do agree on, its transmission fluid changes. "Lifetime" tranny fluid is almost worse than 3k mile oil change hype.

I could perhaps be the only one to disagree (but I do).

The fluid in my '97 SLS is original (157k miles). Shifts beautifully.

The fluid in my '01 STS is original (59k miles). Shifts beautifully.

The fluid in my '03 Grand Caravan is original (75k miles). Shifts beautifully.

I think transmission fluid changes in modern transmissions with modern fluids is also WAY overhyped. Pat Goss swears you need a flush every 30k miles with a BG machine...blah blah blah. I follow the owner's manual on everything else, including using the OLM to schedule oil changes, so I don't see why I wouldn't follow it on transmission fluid service schedules. Has worked wonderfully so far...

**Ranger** · #**137** (**permalink**) 05-03-07, 10:26 AM

Pat Goss! Most guys on this board know more than he does.

jadcock · #**138** (**permalink**) 05-03-07, 10:29 AM

Quote:

Originally Posted by Ranger

Pat Goss! Most guys on this board know more than he does.

I know -- and the fact that he stands FOR frequent fluid changes makes me stand AGAINST them. His whole existance has to be paid by BG products. He recommends their services for EVERYTHING, even brake fluid flushes for Pete's sake.

submariner409 · #**139** (**permalink**) 05-03-07, 12:05 PM

Instead of guessing what normal wear and additive packages do to your engine/oil, spend a few bucks and send your next oil change sample to a testing lab. Starting from scratch doesn't tell you a thing, except for maybe catastrophic amounts of iron or babbit metal in the oil. BUT, 2 or 3 changes down the road, you'll have a good picture of the internal health of your engine, while having spent less than the total for a synthetic oil/filter change, DIY. Your local Peterbilt, Kenworth, or diesel/marine dealer has names and numbers of laboratories, and you'll get a report of EVERYTHING that's in the oil: water, zinc, antifreeze, gas, soot, blah, blah.

**Playdrv4me** · #**140** (**permalink**) 05-03-07, 04:13 PM

Quote:

Originally Posted by jadcock

I could perhaps be the only one to disagree (but I do).

The fluid in my '97 SLS is original (157k miles). Shifts beautifully.

The fluid in my '01 STS is original (59k miles). Shifts beautifully.

The fluid in my '03 Grand Caravan is original (75k miles). Shifts beautifully.

I think transmission fluid changes in modern transmissions with modern fluids is also WAY overhyped. Pat Goss swears you need a flush every 30k miles with a BG machine...blah blah blah. I follow the owner's manual on everything else, including using the OLM to schedule oil changes, so I don't see why I wouldn't follow it on transmission fluid service schedules. Has worked wonderfully so far...

I know where youre coming from...I used to thumb my nose up at tranny fluid changes too...

But then I got thinking about it. The transmission fluid, unlike the motor oil, which is the rock star of the fluid world and gets alot of attention, just sloshes around in there everyday of its life, getting hot, then cold, then hot, then cold, then hot etc etc. It sees some of the highest temps in the car and even HIGHER when towing or theres alot of dead weight in the car. It would in my opinion, take a pretty space age fluid of ANY kind, for this not to absolutely pummel the particles of "stuff" and wear it down in short order.

I have heard one concern with transmission fluid changes, and that is that a flush moves around all the gunk, and metal particles and other shit that had found itself a nice place to lodge without causing any trouble, and theres always a small chance you can really screw something up if this debris ends up in the wrong spot. My answer to that is that if your changing it frequently enough, you shouldnt have anything floating around in there large enough to be of concern. The only other possible side effect is wearing out the gaskets, but a small price to pay versus the cost of a new transmission, and fluid changes arent that expensive.

submariner409 · #**141** (**permalink**) 05-03-07, 04:23 PM

If you think AT fluid takes a beating, what about manual transmissions which use Dexron or Mercon, and also rear end differentials....that 80-120 oil really gets beaten up because hypoid gears slide in and out of engagement by design, and just how fluid is 80W at 10 degrees? Auto transmission fluid has an easy life by comparison, even to engine oils (no combustion contamination or acids...)

**Playdrv4me** · #**142** (**permalink**) 05-03-07, 04:51 PM

Quote:

Originally Posted by submariner409

If you think AT fluid takes a beating, what about manual transmissions which use Dexron or Mercon, and also rear end differentials....that 80-120 oil really gets beaten up because hypoid gears slide in and out of engagement by design, and just how fluid is 80W at 10 degrees? Auto transmission fluid has an easy life by comparison, even to engine oils (no combustion contamination or acids...)

Not sure what your point is... I specifically mentioned transmissions because I assumed diffs were a given. Painted differential housing covers get hot enough to scorch the paint off when youre towing, I change diff fluids even *more* often than I do the A/T goop. It doesnt take much neglect to get the old HHHOOOOWWWLL on your ring and pinion. Not convinced the trans fluid should be neglected though.

jadcock · #**143** (**permalink**) 05-03-07, 07:44 PM

The transmission fluid lives a VERY easy life compared to motor oil. Transmission fluid runs cooler than you think, under "normal" conditions. Again, this is where the transmission fluid life indicator on our cars comes into play. If that fluid overheats, it'll tell you to change it. Towing is probably a non-issue with these Cadillacs...it certainly is with me. If you drive a NYC taxi or sit in NYC style traffic all day, the tranny fluid probably will run a lot warmer and a change would be good. Changing tranny fluid won't hurt anything...some people change it every year I'm sure. It's not bad...just not necessary, under MANY driving conditions (again, I trust the transmission OLM on this one).

Transmission fluid doesn't see blowby contamination. It doesn't see water or fuel. It doesn't really see much of ANYTHING except that for which it was designed. Most modern tranny fluids are also heavily synthetic-based. I know Chrysler ATF+4 is. Not sure on the Dexron III...probably not. I'm sure the new Dexron V or whatever it is now is 100% synthetic.

clarkz71 · #**144** (**permalink**) 05-03-07, 07:52 PM

It does see clutch material, the clutch packs slip as they engage. That's why these transaxles shift so smooth. I wouldn't chance it by not changing my fluid at least every 50K. It's not so much the cost of a replacement part, it's the labor to replace it I wouldn't look foward to. Oh, and the new fluid is Dexron VI, that's what I used at 55K.

jadcock · #**145** (**permalink**) 05-03-07, 07:53 PM

Clark, do you change your engine oil according to the OLM?

clarkz71 · #**146** (**permalink**) 05-03-07, 07:54 PM

I do it when it reads 50%.

**Ranger** · #**147** (**permalink**) 05-03-07, 08:02 PM

50%?! Why?

clarkz71 · #**148** (**permalink**) 05-03-07, 08:05 PM

I can't give you a good reason Larry. I'm working on letting it run further down, maybe 40% next time. Old habits are hard to break.

**Ranger** · #**149** (**permalink**) 05-03-07, 08:10 PM

I hear ya man. Took a long time for me too and much of the Guru's excellent explanations. If it makes you feel any better I recall him saying that the OLM has a 100% safety factor built in to it.

clarkz71 · #**150** (**permalink**) 05-03-07, 08:12 PM

Maybe this will help me....

, almost, I'll keep working on it.