mixing Mobil 1 and dino ATF?

[91QAZ]

I have read many threads on trans flushes and now understand their importance. I have a 91 Q with 91K miles and 32K miles on a new transmission (it has the drain plug). Service history shows that the prior owner did a trans flush about 10K miles ago, and did a drain & refill about 2K miles ago with the 90K nile service just before he sold it. I'll be installing an external cooler next week.

I'd like to switch to Mobil 1 ATF, but since the flush was done relatively recently, I'm not sure a full flush is necessary. I'm thinking of doing this multiple times: drain overnight, fill with Mobil 1, drive for 20 miles, drain overnight, fill....etc. Until I have 95+% Mobil 1 instead of the dino oil. Since my pan has a drain plug, it seems that this should be pretty easy.

Questions: 1) Can I indeed mix Mobil 1 and dino ATF without adverse effects? 2) Anything I am missing or not thinking about correctly? 3) toward the end of this process (better at the beginning?) would a pan drop/filter replacement be wise? 4) how many drain/fill cycles should be sufficient?

Thanks to everyone for their patience with all the newbee questions.

[elwesso]

Tom...

Honestly I odnt see any reason to do that now...... But heres the best way to do that.....

Drain pan, take off pan, replace filter, clean pan, reinstallRefill with M1 ATFRun at idle for *exactly* 2.0 minutesshut offDrainRefillRun for 2.0 minutes

DO that until you have gone through 14 qts... Good as new!

[91QAZ]

Perhaps I'm being overly cautious. I just think I'd feel better knowing that I'm doing all I can to extend the transmission life. EXACTLY two minutes? Explain please. Does this have to do with the time it takes for the pump to circulate a certain amount of fluid?

[elwesso]

This is the amount of time it takes for exactly all the fluid in the pan to get out.. So basically, what youll be doing is circulating the exact amount in the pan, and all that will be in the pan when you drain is old fluid.... At least thats the theory behind the madness

[91QAZ]

I see. Then we minimize the amount of new ATF that gets drained. I like it...

[elwesso]

Doing this method will make me happy... You pay about $60 for new ATF, and then about $100 to use the flush machine..

This method does it almost as good.. PLus if you have a new transmission and the fluid is good, you dont need to use additives to clean things up..... Thus all its good for is a fluid exchange...

I will probably exchange about 6 quarts this summer.... Damn even a nicer better maintained Q45 is expensive.. Gotta pay to play...

[tangalora]

This is a homework question as I will not actually do any ATF fluid replacement until I'm done with the current chain-guide & oil pan job).

My 90 Q45 transmission pan does not have a drain plug.Q1: Where can we order an aftermarket pan that does have the drain plug?

The 90 shop manual recommends 9 1/8 quarts of "Dexron" or "ATF 1".Q2: I saw "Dexron III" at the store (is that the same as Dexron)?Q3: Is "ATF 1" the same as "Mobil 1"?

With synthetic motor oil, it's my understanding we merely trade price for miles (assuming the lower friction of synthetics isn't a major factor).That is, if our dino oil change interval were 3,000 miles at $1 a quart; synthetics roughly get us 6,000 miles at $2 a quart. Point is it's a wash.

Q4: Would it be the same "wash" dynamic for ATF? That is, instead of putting synthetic ATF in every 120k miles (or whatever the recommended interval really is), we should just change the dino ATF at half that interval?

Or is the "Mobil 1" known to work "better" in the transmission on a daily basis? Is any other synthetic ATF brand OK or does it have to be Mobil?

[elwesso]

This is a homework question as I will not actually do any ATF fluid replacement until I'm done with the current chain-guide & oil pan job).

My 90 Q45 transmission pan does not have a drain plug.Q1: Where can we order an aftermarket pan that does have the drain plug?

The 90 shop manual recommends 9 1/8 quarts of "Dexron" or "ATF 1".Q2: I saw "Dexron III" at the store (is that the same as Dexron)?Q3: Is "ATF 1" the same as "Mobil 1"?

With synthetic motor oil, it's my understanding we merely trade price for miles (assuming the lower friction of synthetics isn't a major factor).That is, if our dino oil change interval were 3,000 miles at $1 a quart; synthetics roughly get us 6,000 miles at $2 a quart. Point is it's a wash.

Q4: Would it be the same "wash" dynamic for ATF? That is, instead of putting synthetic ATF in every 120k miles (or whatever the recommended interval really is), we should just change the dino ATF at half that interval?

Or is the "Mobil 1" known to work "better" in the transmission on a daily basis? Is any other synthetic ATF brand OK or does it have to be Mobil?

1: Im sure you could get a new pan from Joe..2,3: Anything that says Dextron will work in the Q45 tranny4. No.. Synthetic ATF is better for the Q45 transmission because of its greater resistance to varnish... However, you should be "ok" using dino if you have a transmission cooler...... It has been proven to reduce transmission temps by about 10F just by using M1 ATF... That is significant, and even with a transmission cooler you may need that 10* sitting in traffic with the AC on....

Im not sure I agree with your "wash" theory... BEcause you have a high quality synthetic does not mean you can double your OCI.... If that were true, techincally you would spend less money, or at least the same..... Lets look at it this way.... We'll use the same filter for both.....

A case of decent oi [dino]l costs about $15..... mobil 1 filter from Joe costs $6 (rounded down)..... So $21 (roughly the cost of a jiffy lube oil change) plus whatever it costs to have it changed (lets not assume that now)... Say 90 day OCI

A case of Mobil 1 ususally costs around $30, so $36 plus filter. Lets say we run that for 4000-5000 (110 day OCI, 4 months).. So its $84 vs $108.. In reality you might be able to extend your OCI a little bit more (assuming you have oil analysis to back this up)...

That extra $28 is worth it IMHO because it keeps your engine clean, and you know you have superior protection... Really, its not a wash.. Any way you slice it its gonna cost more... But you dont run synthetic because it lasts longer, you run it because it can handle things better, and thus less wear on the EXPENSIVE things on the Q... You didnt buy the Q45 to be economical, so you might as well do the cheaper things (like fluids) to extend the life of the expensive things.....

[tangalora]

These are convincing arguments for an external transmission ATF cooler & synthetic Mobil 1 ATF (the temperature drop seems the most compelling). Combine that with Q45tech's photo (copied below) showing the temperature relationship with transmission life) for a 1990 Q45 is important.

For the record, the following NICO threads appear to also back up this argument:

Infiniti Online Mechanic » Transmission Fluid? zerothread?id=32586 (see also gulfoilphilippines.com/Resources/TechnicalUpdate/tu_Changing_ATF_Specifications.htm)

Infiniti Online Mechanic » 95 Q Transmission fluid leak zerothread?id=37805

Infiniti Online Mechanic » Transmission fluid additives zerothread?id=89945

Infiniti Online Mechanic » J30 Transmission Fluid change zerothread?id=81052

Infiniti Online Mechanic » Transmission Fluid Change - Would this work? zerothread?id=76109

Apparently many Q45 cars come with the transmission pan with a drain plug ... but not mine ... and ... since I didn't see anything concrete about the transmission drain plug ... I called Joe's Scottsdale team who recommends a kit consisting of: - 31390-51X02 Transmission pan with drain plug - 31728-51X08 Transmission filter - C1397-51X90 Transmission paper gasket - 31526-41X07 Rubber O ring for the transmission filter

So I took your advice & ordered the whole lot.

P.S. Interestingly, the paper gasket costs as much as the modified transmission pan!

[Jesda]

Can you use RTV instead of the paper gasket?

[elwesso]

No.. There is no groove to apply RTV.....

THe whole kit with gasket, new bolts (they are not reusable), crush washer, is $40

[91QAZ]

Could be wrong on this, but I thought I read a thread that indicated that at least the earlier Q's had no drain plug, but remaned trannys do. Thus, older Q with drain plug MAY mean you have an onther than original transmission (or someone did the conversion that you just ordered)...

[tangalora]

»... the earlier Q's had no drain plug ...

True. Mine is a 1990 Q45 which does not currently have the drain plug.That's why I'm ordering the extra transmission pan (with a drain plug & washer). I'm following NICO advice. It's backordered because so few people buy them apparently.

»The whole kit with gasket, new bolts, & crush washer ...

I just checked with Scottsdale. Wes is right about the bolts.I didn't know (but I do now) that the paper gasket comes with the new bolts.I guess that's why it costs as much as the new transmission pan.

Total cost for the four parts listed above (sans shipping) is a bit over $70 (the strainer alone is just under $30). All I need now is the ATF fluid (I'm still confused where to get it) and the aftermarket cooler & attachments & hoses).

Does the transmission pan & gasket go back on dry WITHOUT ANY RTV?

[squeefoo]

Never heard of non-reusable trans. bolts !?

A friend likened using synthetics in an engine to spending a little extra to buy better fruits, vegetables, and meats for eating. They're both better for you in the long run and are still thrown away when you're done.

A great analogy I thought.

EDIT & PS: If you want to use a sealant on the trans. gasket buy some Hylomar. It's a weird sealant that is made for just this type of use (it doesn't dry). Just a real thin coat for insurance.

[qship96]

Mobil 1 ATF is available at most auto supply stores{ Advance,auto zone, pep boys,etc} price varies 4.79-5.99 per quart in baltimore.

[elwesso]

Mobil 1 ATF is available at most auto supply stores{ Advance,auto zone, pep boys,etc} price varies 4.79-5.99 per quart in baltimore.

I saw it at my local autozone for $29 for a case...

Squee.. I suppose you could reuse them, as they have little things of sealant on them to prevent leaks, i guess....

[squeefoo]

Sealant? or is it some sort of thread lock? Don't know since I've never seen the new Nissan OEM ones.

The trans gasket is reuseable just like the GM ones for the last 10 years.

$30 for a filter !!?? I pay $10 and throw away the paper/composite crappy gasket with it. The $10 filter is a good one too.

[DAEDALUS]

The threads have patch lock elements. Similar to loctite. Comes with the gasket so may as well use the new ones.

[pito11213]

Squee I did the same. When I removed the pan the gasket was so perfect I couldnt believe it. No cracks, no sticking up no nothing. I just put a light RTV on it and bolted it back on.

[elwesso]

The way I see it though, the kit is $40.. I do that once every year or so, and im good for 15-25k...

[tangalora]

I didn't want to quote Joe's prices (that's his job) but I think I accidentally caused some confusion. Wes is right. It's about 40 bucks for the "kit" ($49.01) if you aren't replacing the pan as I am.

To lessen confusion for all, here are the specifics (sans shipping):- 31390-51X02 Transmission pan with drain plug $21.46- 31728-51X08 Transmission filter $27.58- C1397-51X90 Transmission paper gasket & bolts $20.34- 31526-41X07 Rubber O ring for the transmission filter $1.09--- Other materials ---- (assuming a flush is not required)- stopwatch (for the two minute timing)- clear 5 gallon jug (to estimate volume)- paper towels (for the old vs new color test)- small-neck funnel (to pour transmission fluid down the dipstick)- Mobil 1 ATF (at least 14 quarts)

I'm still very worried about the lack of fluid to the rear planetary gear if I don't prime the external cooler & hoses

After reading dozens of NICO posts (I'm writing up a summary but it takes forever to do a good job), I see Dennis repeatedly warns others that the fluid in the external cooler goes FIRST to the rear planetary gear and THEN to the transmission pan. Also Wes notes the pump PUSHES (not pulls) and it pushes MORE than it gets back (I'm not exactly sure why). My (dry) logic tells me the pump would push fluid through the external cooler eventually, but, until the external cooler and the quarter-inch hoses fill with transmission fluid, the rear planetary gear would be getting air for lubricant.

References: Infiniti Online Mechanic » Transmission Fluid Change - Would this work? http://www.nicoclub.com/zerothread?id=76109

Infiniti Online Mechanic » Idling Problem http://www.nicoclub.com/zerothread?id=4000

[tangalora]

Here's another one from Dennis which I will quote verbatim from http://www.nicoclub.com/zerothread?id=85511 (Infiniti Online Mechanic » Transmission: Drain Vs. Flush)

"... the cooler drain return line DOESN'T go to the PAN FIRST, it feeds the critical rear planetary gears then dribbles into to the pan.[That's] why a restricted cooler/line takes out the rear planetary first!"... P.S. This was an interesting comment in that same post:If you are methodical and time the pan drain and run intervals with a stop watch, you can probably safely do a circulating chemical flush and fluid exchange with ATF without a machine?

[qship96]

there is no risk for planetary gear oil starvation using this method whatsoever-even the factory service manual advises doing the same procedure,except it allows 5 minutes of idleing to completely mix the old and new fluid-I think the 2 minute time allows more of the old fluid to be replaced,while conserving diluting the fresh fluid.the reason rear planatary gears are mentioned,is because some people on other boards with other makes of cars will disconnect a cooler line and allow the trans. pump to pump the old fluid into a bucket-therefor interrupting the flow of fluid which causes the planetary gears to starve for oil.this WILL NOT happen by doing the timed drain/fill procedure we are discussing because we are not disconnecting any lines at all on the transmission-the fluid will continue its designed path-hope this clarifies the procedure somewhat.

[elwesso]

I agree... Dont worry about it..... The amount of time the rear planetaries would be without fluid would be very little..... IN fact hardly any risk if the transmission isnt in gear..

Dennis was referring to when the old Q "cooler" would clog.....

If you are methodical and time the pan drain and run intervals with a stop watch, you can probably safely do a circulating chemical flush and fluid exchange with ATF without a machine?

I agree.. may just run an extra cycle just to be safe..... Dont want that stuff in there after its done its job

[maxnix]

For the money, the machines are cheap for the job they do. Trying to fudge it is a risk not worth taking. If Q45tech could find a better and cheaper way, he would use it.

[tangalora]

Dennis was referring to when the old Q "cooler" would clog ...

Assuming together, we've already disconnected both transmission cooler lines & removed the radiator (as per instructions at http://www.q45.org/radiatorrr.html ), is this the transmission part of the reassemble procedure?

- We choose a new transmission cooler based on others' experience- (I think you guys recommend the $50 B&M 70264 but correct if I err)- We search for a good supplier (Joe doesn't sell 'em) & order on the Internet- When it arrives, we attach it in FRONT of the radiator, correct-side up (?)- The location is below condensor pipes & a bit off-center to the driver side- We plug the original brass in-and-out transmission-heater lines on the radiator- We re-install the radiator-and-transmission-cooler assembly on the Q45- We attach the OEM OUT 1/4 inch hose to the BOTTOM of the new cooler (?) - We attach the OEM IN 1/4 inch hose to the TOP of the new cooler (?)

At this point, the car is put back together (but with air in the cooler).With respect to the transmission ...- We drop the transmission pan and throw away the bolts- We replace the strainer & the strainer o-ring- We smear RTV (or equivalent) on the paper gasket & replace- We bolt on the new pan (with the drain plug & washer) using new bolts - We put a thin-necked funnel into the engine-bay transmission dip tube- We drip old transmission fluid onto 5 or 6 paper towels & set aside- We top off the ATF with Mobil 1 using the cold line (engine not running)

AT THIS POINT, ISN"T THE TRANSMISSION COOLER TOTALLY EMPTY?- We start the Q45 & run for TWO minutes exactly (keep engine at idle)- During this time we engage all gears including reverse- We shut the engine (to prevent Mobil1 & dino ATF mixing) at 2 minutes- We open the drain plug on the transmission pan & drip for an hour or so- We test the old color against the new color on a paper towel previously set- We pour old ATF into a 5-gallon clear jug or equivalent (to measure output)- Repeat 4 or 5 drain-and-fill cycles or until the color matches the new

Q: Should we have primed the transmission cooler (it's filled with air)?Q: Where does all that air go (into the transmission & vented off)?Q: Are we saying the time the rear planetary gets AIR is OK?

Thanks for any help in this homework effort (it will help others too).

[elwesso]

Assuming together, we've already disconnected both transmission cooler lines & removed the radiator (as per instructions at http://www.q45.org/radiatorrr.html ), is this the transmission part of the reassemble procedure?

- We choose a new transmission cooler based on others' experience- (I think you guys recommend the $50 B&M 70264 but correct if I err)- We search for a good supplier (Joe doesn't sell 'em) & order on the Internet- When it arrives, we attach it in FRONT of the radiator, correct-side up (?)- The location is below condensor pipes & a bit off-center to the driver side- We plug the original brass in-and-out transmission-heater lines on the radiator- We re-install the radiator-and-transmission-cooler assembly on the Q45- We attach the OEM OUT 1/4 inch hose to the BOTTOM of the new cooler (?) - We attach the OEM IN 1/4 inch hose to the TOP of the new cooler (?)

At this point, the car is put back together (but with air in the cooler).With respect to the transmission ...- We drop the transmission pan and throw away the bolts- We replace the strainer & the strainer o-ring- We smear RTV (or equivalent) on the paper gasket & replace- We bolt on the new pan (with the drain plug & washer) using new bolts - We put a thin-necked funnel into the engine-bay transmission dip tube- We drip old transmission fluid onto 5 or 6 paper towels & set aside- We top off the ATF with Mobil 1 using the cold line (engine not running)

AT THIS POINT, ISN"T THE TRANSMISSION COOLER TOTALLY EMPTY?- We start the Q45 & run for TWO minutes exactly (keep engine at idle)- During this time we engage all gears including reverse- We shut the engine (to prevent Mobil1 & dino ATF mixing) at 2 minutes- We open the drain plug on the transmission pan & drip for an hour or so- We test the old color against the new color on a paper towel previously set- We pour old ATF into a 5-gallon clear jug or equivalent (to measure output)- Repeat 4 or 5 drain-and-fill cycles or until the color matches the new

Q: Should we have primed the transmission cooler (it's filled with air)?Q: Where does all that air go (into the transmission & vented off)?Q: Are we saying the time the rear planetary gets AIR is OK?

Thanks for any help in this homework effort (it will help others too).

No we do not hook the stock "cooler" in the radiator back up...

It doesnt matter if its upside down or right side up... It will be effective either way.....

Basically in summary you are taking the in/out from the transmission and hooking them right into the B/M transmission cooler... NOTHIGN goes into the 2 little things on the radiator...

You want to take a scraper to get the paper gasket off and put a new one on... Your kit that you got is included.. The lazy people above were talking about not getting a gasket

The transmission cooler is empty at this point, but it holds such a small volume of fluid i would consider it a non issue...

Im pretty sure you dont want to engage the gears, just leave it in park...

The fluid goes into the rear planetaries so it will just have air in the transmission pan area.. Again nothign to worry about.. If your really OCD about priming it, dump some ATF in the cooler... Its not like a pump that needs to be primed before it starts pumping.. The pump will push fluid through.. Dont worry about it.....