Frequency of trans oil change and coolant flush?

On my old 308 I did the gear oil every other year, and the coolant yearly. I didn't flush the coolant completely- just drained at the radiator until it stopped dripping, and refilled it. Probably was only replacing 1/2-2/3 of the coolant doing it this way, but it seemed to work. All of the coolant hoses I ever replaced were in great shape.

 

Yes it's time to change out both the coolant and the oil.

 

Time for a change. BMW coolant is not an extended change product...BMW still recommends changing every couple years (at least that is the interval recommeded by my local BMW dealer/and a trusted BMW independant). I am using the BMW stuff in my 355. I would change coolant, transaxle and brake fluids every two years, under normal conditions.

 

I agree, I know on my bmw's it's always been a 2 year change regardless of mileage with bmw coolant. I've owned my car for only 10 months but plan on every 2 year gear oil changes and every 6 month oil changes. If you're doing it yourself, no real cost and not too much time either so why not, just to be sure. Good times, anyway, working on the F car, right?

Jeff

 

Can I use the BMW coolant on my 308 QV?

 

You want to change your tranny fluid every year for these reasons:
1. you purge the system of accumulated condensation (water, even in tranny fluid, will rust bearings and internals)
2. you remove (and potentially detect) debris that could cause your bearings to pit (which leads to catastrophic bearing failure on down the road, so to speak)
3. you will see any large fragments to tell you in advance that you have damage inside

 

I don't see why not. The BMW stuff seems to be highly regarded.

 

3 years or 30k miles right? No wait, 7 years....

 

The main issue with coolant changing is to use distilled water. Tap water is corrosive, distilled water does not even conduct electricity. The BMW coolant is slightly better, but I understand if you do not leave coolant in the car more than a year or two there is not time for the green stuff to turn caustic.
To clear the system, I drain everything then fill with distilled water, drive for a couple weeks, then drain and refill with 50/50 distilled water and BMW coolant. The whole process uses about 5 gal of distilled water.

Mark

 

Thanks, I'll give it a try

 

Scientific explanation? Sound like a call for organic chemist AHAAS, or something like that...a fellow Fchatter. Not my field, but on my cars, I change man trans fluid every whatever(3-5 yrs) but some mfrs say every 80,000 miles, believe it or not. You can get corrosion buildup in the gear oil, even though doesnt get blow by. Heat/hypoid gear pressures get to the oil and breaks down into sludge. AHAAS needs to chime in here and give us a 1-2 pg course.....

AS far as the BMW coolant, we discussed this a few months ago at some length along with the phosphate additives being good or bad, etc etc etc......The extended coolants are the way to go these days. No more coolant change every year.

 

Short course:

I change a new car’s coolant after 1 - 1 1/2 years and use a G5 type (as MB coolant). I would then change it a year later. From then every 4 years is OK. It takes that many changes to get all the old stuff out. If you race the car you need to change more often.

In the Murcielago, you can only change about 1/3 - 1/2 of the fluid in a given change. I changed it after a year, I drove the car a week then changed it again to get more of the original stuff out. I will change it once in another year then probably do it every 2 years even though the fluid is good for 4 years.

Coolant is also the water pump lubricant. If you want to keep those bearings as new, change the coolant often, just like your oil. And use the appropriate concentration. There is an optimum percent, sometimes it is 40 percent and other times it is 50 percent, it could be something else. There are valves for the heater core that need lubrication too.

Do not use distilled water, use tap water. Pure, distilled, de-ionized water is very polar and corrosive.

I change transmission fluid after the first year or around 2,000 miles then every 2 years or 5,000 miles. Time and mileage are both limiting values for all oils.

For automatic transmissions as in the Expedition I change it every 15,000 miles and I do not carry heavy loads.

aehaas

 

Wow, thanks for the quick response, Ali!

But wait.....no DI in coolant?? Corrosive? Hmmmm. What about the Calcium content of some tap waters, especially here in FL? Some Calcium compounds are also known to be more corrosive than say, DI water, no? Not to mention the caking properties of said Ca compounds......thanks in advance for your advice.....

 

Consider this. Water is a solvent for almost everything. As such there is a maximum saturation amount for every material in water. Up to this amount the material continues to dissolve, and then dissolution stops. (Well, technically not really, as dissolution and solidification continue when they reach equilibrium, but close enough.) Since distilled water has essentially nothing dissolved in it, it is far from the saturation point and is thus quite corrosive for many materials.

 

For coolant, I use Prestone's 50/50 pre-mix. Sharp guys there; they use the right water. Can't go wrong with the pre-mix coolant.


But when I have had to use tap water, I've only used filtered tap water (not raw tap water).


As for tranny fluid, if you think that you don't want to change it every year (my suggestion is 1 change per year), at the very least drain your tranny fluid into a glass bottle and let it sit overnight.

Observe the amount of water on the bottom of your glass the next morning. This will give you a rough idea for how much condensation you are accumulating with your driving habits in your climate.

That water will rust your internal gears and bearings in your tranny. Changing your tranny fluid often will greatly limit the amount of damage from such built-up condensation.

 

That is really not right. De-ionized water is very corrosive for basically the reasons you state. Distilled water on the other hand has bad stuff removed, like chlorine that is very very corrosive and calcium that causes scale and fouling. Tap or De-ionized water is a bad idea, distilled is the way to go. It will leach a bit of the metal away, but not much and when coupled with the corrosion inhibitors in coolant will provide you many many years of worry free service….provided you change it every 2-3 years, mainly to replenish the corrosion inhibitors, but also to prevent fouling (material dissolved from 1 component being deposited on another) and ensure stable freeze and boiling point.

In most parts of the country a 70/30 water/coolant mix will work the best….it’s the water part that does most of the work cooling, the “coolant” helps with freezing/boiling points and adds corrosion protection. It you are going to drain it every winter and are struggling with overheating, distilled water with water-wetter cools the engine about the best, but is not necessary for most applications

 

I appreciate your comments, guys, but, as usual, the DI vs distilled, evolves into a tech talk, which, hey , I welcome, as long as you do....

Not true that distilled has had the Chlorine taken out, but DI has not. Totally false, probably an old wives tale or sacred cow that some refuse to kill.....I sell it, and certify it and occasionally, the sacred cow shows its ugly head with a customer (usually government employees) will ask for an MSDS for it!!!! The world has gone nuts!

DI is the SAME as distilled, except for the most demanding of scientific research applications. For us crude radiator guys, NO difference. Now, to use tap with coolant is just messing up with impurities the coolant mixture that the factory engineers have worked hard to balance for us with the proper corrosion inhibitors/ph buffers, lubricants, etc etc. Water being corrosive is , well, a misuse of the definition, as we typically understand it, and frankly, incorrect. Cripe, my kids drink DI/distilled water every day!!!!!

When one advises to add tap vs just pure, one will be adding the calcium which, as you mentioned above, will contribute to SCALE. AND calcium compounds are way more corrosive than DI. Not to mention some magnesium. Even if di/distilled was corrosive, when mixed with 100% coolant, the compounds in it will alter the new mixture, the DI doesnt continue to be DI anymore!! Get it? No more sacred cow........Sometimes , what they refer to as "bad" science is still preached, and no reasoning can erase it......

 

DI is very much not the same as distilled. Yes both DI and distilled have the contaninates removed and that's good. The problem with DI is that it has also had nearly all the ions removed as well....and way it's called DI. DI water very much wants it's ions back and is very corrosive to almost everything until it gets them... and needs to kept in plastic if you expect it to remain DI. Having spent a couple years dealing with DI in fuel cell cooling systems (we needed a completely non-conductive coolant), I can say with great certainty that DI is not what anybody really wants to pour into their cooling system. In a metal environment it won't stay DI for very long because it sucks ions out of the metal, which is the definition of corrosion. I guess as long as you don't change it out every weekend like racers often do, it's probably not going to ruin anything, but it's not what you should be using. Distilled is what you want.

 

DI and distilled water may be exactly the same or not. The manufactures of these types of clean water produces say NOT to hook these units up to your house plumbing. The reason is high corrosion.

The manufactures of the coolant assume we, the end use, will be using regular water and they account for that. I looked into this for some time then finally decided to use just tap water to dilute coolant.

aehaas

 

You may be exactly right, but it still makes me a bit uncomfortable to add calcium and chlorine among other things to the cooling system on purpose...they are just bad. I guess if the coolant has something that binds them up and holds them in solution. You’re the chemist, so on this one I’ll take your word for it, but just the thought of tap water in the fuel cell cooling system used to make the electrochemists wince...but part of that was the conductivity losses for sure.

I think planned obsolescence is a key part of most decisions these days and they know tap water with normal service over the 10 year life expectancy is fine….but it’s got a lot of stuff in it and my car is 25 years old……

I just read the water wetter tech page and they use the term "plain water" everywhere, but then the water specs are for pure (distilled or di) water. very confusing.

 

Now that I've actually though about it you are probably exactly right, they are just different process for accomplishing the same thing....my bad. We always referred to DI by a conductivity valve, it was simply add no free ions rendering is non-conductive and the “other” stuff was the distilled water because although it was clean, it still had metal ions from the distilling equipment, but I guess that doesn’t have to be true.

 

Also, the tap water in Southern California has flouride added. I have heard this may help the TEETH in your gear box !

LMAO

Regards,

Stew

 

Good one, Stew!! Who knows what tap has in it around the country.....Too much Calcium here, too much iron there, too much chlorine, fluorine..........Tap is..., well, just tap!