F250

For those who, like me, have only a partial tow prep package installed, you may well be missing the engine oil cooler. On my vehicle, I have the tow hitch receiver, four-prong flat harness, and transmission cooler already on the vehicle, but the engine oil cooler simply is not there. I am also thinking that the trailer wiring controller is missing as well, but have not taken the time to yet confirm that. Consequently, I've been researching the parts requirements for adding the engine oil cooler, and it is not as straight forward as one might hope.

In order to get a complete system, the oil cooler will need to be added, and possibly the trailer wiring controller. The wiring controller is not that big of a deal, and is only about $35 and not too difficult to install. The oil cooler, on the other hand, is not a simple task, nor is ti cheap. The Lexus cooler, discounted at various Lexus parts sources, is about $720 by itself (15710-31030), but you also will need a new cooling Water Inlet (16321-31020), cooling Water Outlet (16331-31190), two cooling hoses (haven't located parts numbers for supply & return to and from the cooler), an adapter Bracket (15781-31010) which mounts between the oil filter head and the oil cooler, Bracket O-ring (90301-67004), and the lower double oil line pipe arrangement with its two gaskets (TSB kit 04004-29131).

Well, eBay is your friend. You can get a used Lexus oil cooler (the expensive part of this project) online for anywhere from $95 to $350. The water inlet and outlet seem to be just Lexus parts at this point, but the lower oil line is also on eBay for $65-$75 including its two gaskets. Guessing that the two cooling water hoses will run in the $50 range at Lexus, you could potentially do this "Engine Oil Cooler Add-on" project for $325 - $525 with used parts, but the project with NEW parts will come to about $$1,020. If you need to add the transmission cooler, aftermarket coolers can be had for less than $150, but then you may have hoses to purchase as well. Then there is the trailer wiring controller for about $35.

Therefore, if you're starting from scratch and want to add the tow package where it did not exist before in any manner, the total parts price is going to be about $1400 for new parts, and as little as $650. If you can do all the bolt-ons yourself, that's great, but if you need dealers or shops to do all the installation, your total out-the-door cost is probably going to be in the neighborhood of at least $2000, and probably closer to $2500.

Personally, with a combination of the parts I already have and the fact that I really have virtually no reason (or extremely rare need) to tow with my RX450h, it's becoming harder for me to justify adding anything except the potentially missing wiring controller. You, however, may be in a different situation and feel a stronger need for this extra equipment.