Do I need a transmission cooler for towing?

[SoCal_M3]

I'm planning on using my 2010 X5 35d to tow a 3000lb car on an open trailer. Do I need to be thinking about a transmission cooler or anything like that?

[Krunk Man]

nope your fine

[ard]

Huh, this should be interesting.

BMW is amazingly silent on "all things towing".

-They do not 'rate' their vehicles as tow vehicles; no GCWR, no GVWR.
-The hitch has a rating, but is installed by dealers- not the company that makes the vehicle. This absolves them of such requirements.
- Unlike most cars and trucks, there is no altered maintenance or transmission maintenance for heavy towing applications

I suspect that they decided that their 'exposure' to warranty issues is very limited since 95-98% of owners will never tow, and those that do will tow rarely. Any issues due to transmission overheating, etc, will be limited and just cheaper to deal with the handful that occur within the warranty period than deal with the confusion and expense of 'severe duty maintenance'.

But I'm a cynic. Others will surely say "those BMW engineers thought of it and no coolers and no altered maintenance is the very best plan to get 200-300k out of your X5 as a tow vehicle".

So....

Unfortunately we have no clue as to how hot the FRIGGING ENGINE gets in our X5d, let alone tranny!!!! BMW engineers have determined that us americans would be confused by an engine temp gauge, so thats gone... dropping in a SPA gauge with tranny and engine temp would be sweet, especially if you will be towing a lot. EGT would be good too. (Have all 3 on my tow vehicle, F250 PSD)

But to answer your question ( ) : No, no cooler "required"

A

[JCL]

I disagree. A cooler is definitely required. The good news is that there is one installed on all X5 models with an automatic, from the factory, so no additional cooler is required. As Krunk says, you are fine. The cooler is thermostatically controlled. The thermostat is not the same as the engine coolant thermostat. This cooling system is one reason that the X5 transmissions don't tend to wear out (although they do tend to break). I don't know the thermostat setting, but someone with technical manuals may have the spec.

While I have never seen a GCWR published, there is certainly a maximum tow rating published by BMW, and there are limits published for maximum drop and reach for the hitch ball. There is also a braking requirement published for trailers over a certain weight. So I do think that BMW has considered towing, and isn't completely silent on the issue.

BMW also mention more frequent service requirements under the label of severe service in their maintenance recommendation (in my vehicles, not sure about the 2010 model), and heavy towing could certainly apply in that case.

Having said that, look up posts by withidl on this board. He regularly towed 8000+ pounds of Airstream with his E53, over the continental divide many times, and never had any transmission issues. I think the transmission does not have issues with overheating. It does have other issues, but I don't think they are impacted by towing.

But then, I'm not a cynic

[ard]

Originally Posted by JCL

I disagree. A cooler is definitely required. The good news is that there is one installed on all X5 models with an automatic, from the factory, so no additional cooler is required. As Krunk says, you are fine. The cooler is thermostatically controlled. The thermostat is not the same as the engine coolant thermostat. This cooling system is one reason that the X5 transmissions don't tend to wear out (although they do tend to break). I don't know the thermostat setting, but someone with technical manuals may have the spec.

While I have never seen a GCWR published, there is certainly a maximum tow rating published by BMW, and there are limits published for maximum drop and reach for the hitch ball. There is also a braking requirement published for trailers over a certain weight. So I do think that BMW has considered towing, and isn't completely silent on the issue.

BMW also mention more frequent service requirements under the label of severe service in their maintenance recommendation (in my vehicles, not sure about the 2010 model), and heavy towing could certainly apply in that case.

Having said that, look up posts by withidl on this board. He regularly towed 8000+ pounds of Airstream with his E53, over the continental divide many times, and never had any transmission issues. I think the transmission does not have issues with overheating. It does have other issues, but I don't think they are impacted by towing.

But then, I'm not a cynic

Knew I'd see you here!

BMW does not publish a CVWR or CGWR for the X5. If you've seen one, love to see it. We're splitting hairs (hey, why not, I've got Tivo) but the term "rating" is loaded. Saying the hitch has a maximum of 6000lbs is different than certifying the VEHICLE with a tow capacity. I've seen very little from BMW on this.

Likewise, love to know the tranny temps when towing a 6000lb trailer up a 6 mile 5% grade....

FYI- BMW has no increased maintenance schedule based on towing, or 'severe service' or anything else...one size fits all when BMW is paying! - tranny fluid good to 100,000 miles NO WORRIES.



A

[JCL]

Originally Posted by ard

Knew I'd see you here!

BMW does not publish a CVWR or CGWR for the X5. If you've seen one, love to see it. We're splitting hairs (hey, why not, I've got Tivo) but the term "rating" is loaded. Saying the hitch has a maximum of 6000lbs is different than certifying the VEHICLE with a tow capacity. I've seen very little from BMW on this.

Likewise, love to know the transmission temps when towing a 6000lb trailer up a 6 mile 5% grade....

FYI- BMW has no increased maintenance schedule based on towing- tranny fluid good to 100,000 miles NO WORRIES.



A

I have never seen a combined weight rating published. We could extrapolate based on the published maximum trailer load plus the vehicle weight rating, but I think that would give an optimistically high figure. Realistically, if you are fully loaded in the X5 you probably shouldn't also be at 6000 lbs of trailer weight.

While there are various hitch ratings (6000 lbs, 7800 lbs in Europe, etc) the vehicle has a published tow rating of 6000 lbs. That isn't for all models; for example, the E53 six cylinder with five speed automatic was limited to 5000 lbs due to the transmission, even though the hitch sold for it was the same 6000 lb hitch. The six speed automatic in the 3.0 went up to 6000 lbs, same as all the V8 models. There was a 7800 lb rating published on a European BMW factory site for the E53, but I think it was an error based on the Westfalia hitch being rated at that figure. Westfalia point out that their 3500 kg hitch (7700 lb) does not override BMW's vehicle tow rating.

Also, the published vehicle tow rating without trailer brakes is (from memory) 1600 lbs trailer weight for all models, so they have considered vehicle brake limits as well.

I will look for transmission temperatures. I suspect that judicious use of the steptronic selector can keep them down, by manually selecting a gear if the vehicle starts to 'hunt' on a long grade, and ensuring that the vehicle has the torque converter in lock-up mode as often as possible. Transmission temperatures would vary widely on that long grade, depending on the above.

My warranty and service guide talks about the maintenance intervals being based on normal use, and advises that 'severe service' such as very dusty conditions, extended idling, etc, should be considered as reasons for reducing the recommended service intervals, ie increasing service frequency. It is a general guideline that isn't reflected in the i-Drive maintenance intervals AFAIK. I also don't know if they reference severe service in the 2010 manuals or the 2010 warranty and maintenance guide.

[ard]

Originally Posted by JCL

I have never seen a combined weight rating published. We could extrapolate based on the published maximum trailer load plus the vehicle weight rating, but I think that would give an optimistically high figure. Realistically, if you are fully loaded in the X5 you probably shouldn't also be at 6000 lbs of trailer weight.

I agree it isn't published, and I assert BMW does not do this for a reason!

Originally Posted by JCL

While there are various hitch ratings (6000 lbs, 7800 lbs in Europe, etc) the vehicle has a published tow rating of 6000 lbs.

Where is this "published" for the USA, or is it a reference to a hitch rating?

Originally Posted by JCL

That isn't for all models; for example, the E53 six cylinder with five speed automatic was limited to 5000 lbs due to the transmission, even though the hitch sold for it was the same 6000 lb hitch. The six speed automatic in the 3.0 went up to 6000 lbs, same as all the V8 models. There was a 7800 lb rating published on a European BMW factory site for the E53, but I think it was an error based on the Westfalia hitch being rated at that figure. Westfalia point out that their 3500 kg hitch (7700 lb) does not override BMW's vehicle tow rating.

I don't think BMW has published a US vehicle tow rating... there is nothing in any of my 2010 manuals...and if it isn't ON the car or IN the manual, then BMW hasn't "said" it. From a legal/regulatory perspective.

Originally Posted by JCL

I will look for transmission temperatures. I suspect that judicious use of the steptronic selector can keep them down, by manually selecting a gear if the vehicle starts to 'hunt' on a long grade, and ensuring that the vehicle has the torque converter in lock-up mode as often as possible. Transmission temperatures would vary widely on that long grade, depending on the above.

Yup. Would be of interest. And agree that HOW you drive can dramatically impact the drivetrain...with any tow vehicle.

It really is interesting to see how little BMW really has "published"...

Originally Posted by JCL

My warranty and service guide talks about the maintenance intervals being based on normal use, and advises that 'severe service' such as very dusty conditions, extended idling, etc, should be considered as reasons for reducing the recommended service intervals, ie increasing service frequency. It is a general guideline that isn't reflected in the i-Drive maintenance intervals AFAIK. I also don't know if they reference severe service in the 2010 manuals or the 2010 warranty and maintenance guide.

I have the 2010 maintenance and service guide on pdf. Nothing. How could BMW do their little CBS system if owners said "Oh, I was towing a lot"?

A

[scollins]

Page 271 of my 2010 manual shows the GVWR for the various E70 X5 models (but does not show a GCVW figure.)

For mine: 2010 X5 35d with 3rd row.
GVW - 6,614 lbs
Load - 1,290 lbs
Rear Axle - 3,858
Front Axle - 3,064

But, I can't find anything in the manual or on BMW's website that says anything about towing. However, the hitch installation instructions offer this:

• The BMW X5 hitch is rated Class 3 (gross trailer weight 6,000 lbs, maximum tongue weight 600 lbs.) NEVER exceed these specifications. This rating is based on a standard equipped vehicle with driver. Additional passengers and/or cargo will reduce maximum vehicle/trailer ratings."
• Do not exceed gross vehicle weight or front/rear axle weights as specified in the vehicles owner's manual and displayed on the Safety Certification Label located on the driver's door jamb.
• Do not use weight distribution equipment.

So, BMW says it is rated at 6,000 lbs max with vehicle/driver. We can surmise a GCVW rating with all this information.

On BMW's website, the unladen weight is listed at 5,192 lbs, so let's add 200 lbs for a driver and we are at 5,392 as the "wet weight." Alternately, Max payload is listed as 1,290 lbs with a GVWR of 6,614 lbs. This gives us a "wet weight" of 5,324, which is close to our figure above. Let's go with "vehicle plus driver" as being 5,350 lbs. Add 6,000 lbs to that and we have a GCVWR of 11,350 lbs. Let's round that down to 11,000 lbs max GCVWR.

So, if we have a fully loaded X5 (6,614 lbs max), our max trailer capacity is now 4,386 lbs.

For my own towing needs, I figure it this way:
Driver - 250 lbs
Passengers (wife and 2 young kids plus boosters) - 300 lbs
Tongue weight - 500 lbs
Subtotal - 1,050 lbs.
Remaining payload - 240 lbs (workable.)

My trailer weighs in at 3,500 lbs max, but we are usually towing at 3,000 to 3,250 lbs. So I'm still well below the 4,386 lbs max towing with a fully loaded X5.

I haven't actually towed with it yet (don't even have the hitch installed), so we'll see how "reality" compares to my "theory."

[JCL]

Originally Posted by ard

I agree it isn't published, and I assert BMW does not do this for a reason!


Where is this "published" for the USA, or is it a reference to a hitch rating?


I don't think BMW has published a US vehicle tow rating... there is nothing in any of my 2010 manuals...and if it isn't ON the car or IN the manual, then BMW hasn't "said" it. From a legal/regulatory perspective.


A

I have to use the E53 as a reference, and the E83, as those are the two models of OE hitch I have installed. I don't have the E70 instructions handy, but I can't see why they would be any different.

For the E53, and the E83, BMW provides the vehicle ratings in a technical document that is packaged with the hitch. I wanted another copy, so I had my dealer print me one out, it has an SIB number. That document stated the following:

Originally Posted by BMW E53 Hitch Instructions (extract)

All X5:
Max towing weight for trailers w/o brakes (on and off road) 1650 lbs.
Max tongue weight for trailers w/o brakes (on and off road) 330 lbs.
Max towing weight for trailers w/ brakes (off road) 3300 lbs.
Max tongue weight for trailers w/ brakes (off road) 330 lbs.

8 Cylinder/Automatic transmission:
Max towing weight for trailers w/ brakes (on road) 6000 lbs.
Max tongue weight for trailers with brakes (on road) 600 lbs.

6 Cylinder/Manual transmission:
Max towing weight for trailers with brakes (on road) 6000 lbs.
Max tongue weight for trailers with brakes (on road) 600 lbs.

6 Cylinder/Automatic transmission:
Max towing weight for trailers with brakes (on road) 5000 lbs.
Max tongue weight for trailers with brakes (on road) 600 lbs.

If I had a clean copy, I would scan it for you, but the last time someone asked I typed it, so I just cut and pasted here.

For the 2004 model 3.0, with the 6 speed automatic, this was updated to 6000 lbs. The 5000 lb limit remained for the 5 speed GM automatic transmission.

There was also a table (and a label for the hitch) that specified maximum hitch ball dimensions from the receiver, in terms of reach and drop. Those limits were based on the vehicle structure, not on the hitch fabrication, in my opinion, since the hitch is far stronger than the rear pan of the X5.

I conclude from the above that BMW did calculate the safe load based on vehicle platform limits, even down to the transmission model, and not on the hitch rating, since they all used the same hitch.

BMW did not need to put this in the owner's manual (but it would have been nice if they did) since the owner's manual states that no non-BMW accessories are permitted. In other words, the vehicle tow rating with an aftermarket hitch is zero as far as BMW is concerned. Use one at your own risk. Buy the BMW hitch, and they provide the info. My hitch was built in the US, and the instructions were from BMWNA, not BMW CA.

Perhaps someone who has installed the E70 hitch themselves can clarify what the hitch instruction manual states for that model.

Edit: Sorry, hadn't read scollins post yet. There are the BMW weight limits for the E70, from the E70 hitch installation instructions, part number 01 29 0 412 716. Those instructions state that the hitch kit includes a capacity sheet (handout) to be left in the vehicle for the owner.

[JCL]

Originally Posted by scollins

For my own towing needs, I figure it this way:
Driver - 250 lbs
Passengers (wife and 2 young kids plus boosters) - 300 lbs
Tongue weight - 500 lbs
Subtotal - 1,050 lbs.
Remaining payload - 240 lbs (workable.)

My trailer weighs in at 3,500 lbs max, but we are usually towing at 3,000 to 3,250 lbs. So I'm still well below the 4,386 lbs max towing with a fully loaded X5.

I haven't actually towed with it yet (don't even have the hitch installed), so we'll see how "reality" compares to my "theory."

I think you are being safe and conservative. You may not want 500 lbs tongue weight with a 3500 lb trailer, 350 minimum is a good target.

Unless you are referring to your trailer axle weight instead of your trailer weight, you don't need to subtract tongue weight. You calculate 300 + 240 = 540 lbs, 6000 - 540 = 5460, so you could tow 5460 and you are planning on towing 3250, which is lots of safety margin.