1968 Mustang Automatic Transmission Fluid?

macgeek · 09-02-2008

Well silly me, I accidentally put the wrong type of fluid (ATF+4) in my 1968 hardtop's automatic transmission! I went to the auto parts store, and they told me that that was bad news, and that I should have the whole thing drained at Jiffy Lube ($120). But he told me to get a second opinion, so I went to the other auto shop in town and the guy there told me that using ATF+4 instead of Type F shouldn't matter, that it's just Chrysler's name for synthetic automatic tranny fluid. How big of a problem is it, honestly, to use ATF+4 instead of Type F, or mixing the two? (the second guy also said adding Type F to the quart of ATF+4 that I accidentally added is fine) I've read that you should ONLY use Type F, so I'm not sure who to trust here. I'd really like to not have to shell out $120 to get the tranny flushed. Thanks!

squidbilly · 09-02-2008

I would read the ATF +4 bottle to see if it says specifically that it is incompatible with type F fluid. I had a parts guy try to sell me some fluidd that was incompatible with type F once. You can change the fluid yourself for about $15 (new trans gasket, filter & fluid). If you are wrried about it that would be he cheapest way to do it.

heavy metal · 09-02-2008

Welcome to the site!!!!Like he said above,just pull the pan and filter,reinstall with type F fluid.

67stallian · 09-03-2008

OUCH!!! If you're lucky and you didn't drive for long you may get away with doing a complete flush. Type F and Dexron or the type 4 stuff have different additives in them. Type F in a Dexron system would cause a harsher shift which could damage but Dexron or Type 4 in a Type F system would cause band slipping if you didn't smell that plesant burning smell from your transmission then you may get away with it. Bottom line you can't switch one fluid for the other!!! No matter what the guy told you at the parts store.

macgeek · 09-03-2008

The ATF+4 bottle doesn't mention anything about compatibility with Type F. The guy at the first auto shop said that dropping the pan myself would leave up to like 3/4 of the fluid still in the system, especially if it gets in the torque converter. I haven't started it up since I put the fluid in, but I also haven't driven it anywhere yet and it's not street legal, so I don't think I could get it to the Jiffy Lube without a trailer (which I also don't have). The guy at the second auto shop sounded pretty darn sure that ATF+4 wouldn't hurt the transmission, but the guy at the first shop said the slip additive isn't handled well by the Ford tranny (he only mentioned the slip additive as being a problem). I'm hoping I can get away with the ATF+4 and just add Type F to finish up the job, and only use Type F in the future of course. Out of curiousity, what's the worst case scenario in this situation? Thanks again.

heavy metal · 09-03-2008

If you have not started it since the wrong fluid was put in,then it is not in the convereter.Go ahead and drop the pan,put in the correct fluid.

67stallian · 09-04-2008

I don't even want to start with why a whole bunch of these parts shop guys shouldn't be working in the business. But the two shouldn't be mixed. Heavy Metal has it right 3/4 of the fluid that's in the system is in your torque converter and will still be Type F if you haven't started the car. Buying another 4 or 5 bottles of fluid with a new filter kit is a lot cheaper than cooking your transmission bands and doing a complete overhaul.

SBPony · 09-04-2008

I just had mine rebuilt and found that a reliable trans shop should be able to set you in the right direction. Anyone heard of using hydralic fluid in place of regular tranny fluid? Have seen alot about it on the racing sites and it does hold up better to heat. Wasn't willing to risk a new 1,200 dollar trans without a little more info.

macgeek · 09-04-2008

Both of the guys I talked to work in auto body shops, not parts stores, so I figure they know a little more about what they're talking about. Sounds like dropping the pan is what I'll be doing. Since I've never done this before, what all does it involve? I'll need new fluid, obviously, and a new filter... anything else? Thanks.

67stallian · 09-04-2008

If you can find a filter kit with a neoprene pan gasket those usually seal the best, I personally can't stand the cork gaskets they never seem to seal properly. Other than that, all the tools (which isn't much) and you're good to go. As for SBPony's thoughts on hydraulic fluid, only thing I could find was the supershift racing fluid. They say it's not recommended for stock transmissions, too positive of a shift (too hard). They also say not to mix with stock fluids, shortens it's life. But I'm not a track guy (car's just not fast enough...lol) so you might have a valid point.