I realize that two shops have said ‘don’t worry about it’, but, in my opinion, they’re wrong. The one thing we’ve seen consistently cause folks major problems here are transmission issues. Unless abused, engines pretty much run for 200k miles. But an overloaded transmission can fail much sooner. I would NEVER tow with your setup without an extra cooler for the transmission.
NEVER.
FoDaddy- I corrected the total weight to 1600 lbs.- A mechanic at the Toyota dealership me not to worry about it- the trans. oil is already routed through the radiator... just do a trans. service at 30,000 miles- I'm towing once a year, flat terrain- The mechanic at U-Haul who installs after market coolers said the same thing- I realize everyone has an opinion!
Most vehicles automatic transmissions are cooled through the bottom section of the radiator. This isn’t new. The problem is that when towing it really puts a lot of stress on the transmission…and current tranny cooler may NOT be efficient enough. The whole idea of adding an auxiliary cooler is to help cool the tranny fluid a lot better. The auxiliary tranny cooler is 5-10 times the capacity of the little bottom part of the radiator.
You can do what you want…but even with my 4runner I wouldn’t tow anything over 1500lbs without and auxiliary cooler. Tranny cooler is far cheaper then a new transmission.
I’m on board with the tranny oil cooler, but if you decide not to do that, I will suggest that when you return from your trip, have the ATF checked. It may suffer some breakdown from the trip so it would be a good idea to get the ATF changed at the first sign of discoloration. You may find that an aux cooler is cheaper than all the extra ATF changes you might need. Your first trip will let you know.
As for the engine oil, I’d suggest that you go with a full synthetic oil if you don’t already. It can tolerate higher temperatures. If you use conventional oil, be sure to check it every time you fill up with gas. Sustained high speed driving with a load will make the oil run hotter so you may get some burn off just from the excessive heat, not from the usual sources of oil burning. This can happen even if you are not currently burning oil, and if it does happen, that does not mean that you will burn oil in your normal driving.
If you use conventional oil, check it often and do not let it drop more than a half a quart, or it will run even hotter. Conventional oil today is good to about 350°F before it starts to burn, synthetic is usually good for 450° Your oil is not likely to hit 350, but it might get close to that.
OP, there are 2 problems with radiator trans fluid coolers. One is the potential over time to develop a leak which can allow engine coolant to mix with the trans fluid and ruin the transmission. The odds of this happening with your Toyota are very remote, but the possibility is there.
Regarding what you were told by those people, the problem with radiator coolers is that they’re using hot 200 degree engine coolant to cool transmission fluid and a much more superior method is to cool the fluid with air flow through an auxiliary cooler.
Did either of those people mention the above?
Regarding the total weight, you mention the trailer/Harley weight but what figuring the weight of items packed inside the Highlander?
I’m now getting the picture-
I would spend the bucks for the cooler if it was I, me? whatever Grammar police should let me know.
@PricePhoto I realize everyone has an opinion"
I think everyone’s opinion has been pretty consistent given what you originally gave for information. NOW that we know it does have a cooler, the weight towing is almost 1000 lbs less then originally thought and, you have consulted with a Toyota dealership, I hope you can see that the advice could be all over the map given these changes. @FoDaddy was spot on given the original info. Sometimes we just read your original post, assume it’s the facts as stated and give a solid opinion. Sorry for the confusion…but it is legit. I have changed given the new info too. Take care.