cmigliet Report post Posted April 30, 2018 Boneheaded move! I accidentally put a qt of automatic transmission fluid in my caterpillar 3126 diesel oil. will it damaage the engine? Share this post Link to post Share on other sites
dickandlois Report post Posted April 30, 2018 25 minutes ago, cmigliet said: Boneheaded move! I accidentally put a qt of automatic transmission fluid in my caterpillar 3126 diesel oil. will it damaage the engine? The ATF just being added to the oil will not hurt the engine, BUT you will need to drain all the oil - if you have run the engine, then change the oil filter. Not a good idea to run the engine for any length of time !!!! Rich. Share this post Link to post Share on other sites
wolfe10 Report post Posted April 30, 2018 Agree. And if any miles on the current oil, I would just use this opportunity to do normal oil and filter. If it has been run with ATF in it, perhaps with the drain plug out, pour a quart of new oil through it to flush a little more of the "mixed oil" out. Share this post Link to post Share on other sites
wildebill308 Report post Posted April 30, 2018 2 hours ago, cmigliet said: Boneheaded move! I accidentally put a qt of automatic transmission fluid in my caterpillar 3126 diesel oil. will it damaage the engine? Glad I wasn't there when you looked at the bottle and realised what you had done. It might have been hard on my ears. By the way welcome to the forum. I agree with the others that it would be best to change it and not run it much with the ATF in there. You should be just fine doing a regular oil and filter change. One quart in 19 isn't a major issue but does need to be addressed. Hope you had not just done a oil change. Bill Share this post Link to post Share on other sites
hermanmullins Report post Posted May 1, 2018 Do I remember putting a bit of ATF in the oil just to get a bit of cleaning action before an oil change? Not running it long but long enough to coat everything the drain it out. I do recall putting a bit through the carburetor to clean the top end. Man what a cloud of smoke it would make. Herman Share this post Link to post Share on other sites
wolfe10 Report post Posted May 1, 2018 Herman, Ya, remember running it through the carb, but not the oil. Share this post Link to post Share on other sites
fagnaml Report post Posted May 15, 2018 Here's a quick response from me the "Refining" guy. The "base oil" used in transmission fluids and gasoline engine oils (think 5W-30, 10W-30) is the same base oil know as 100 Neutral Oil but that is where the similarity ends. The additive packages are drastically different in that transmission fluids do not have "viscosity index improvers" to give protection at high engine operating temperatures. It would be OK to drive your motorhome a short distance (5 - 10 miles) to your favorite service center for an oil and filter change. There is no need to flush the small amount of "mixed oils" you now have in the engine after the oil is drained. That residual amount won't impact the 4+ gallons of new oil. Share this post Link to post Share on other sites
