Hi all, long time lurker first time poster. I have learned a lot from this forum and searched quite a bit but didn't find exactly what I was looking for so it's time to ask the experts!!
I have a 2013 F150 ecoboost that originally came with an open 3.31 rear. I eventually ditched the stock wheels and tires and put some 35" Nitto Trail Grapplers which absolutely killed the power in the truck. I then swapped to 4.56 gears and added a Detroit true trac in the rear. I know Eaton recommends a mineral based oil but allows a synthetic preferably without friction modifiers.
The place I had the rears done absolutely recommended a mineral oil and never a synthetic. I did the break in for 500 miles with Mobilube HD 85w140. Dumped it and refilled with the same. It's been in there now for about 20k miles. No problems or weird noises.
Just for kicks I took some of the Mobil 85w140 and put it in the freezer overnight in a solo cup. It had nearly turned solid!! I turned the cup upside down and it didn't flow at all. The freezer temp is set to zero degrees. I did the same test with Mobil 1 75w140 I had laying around and it was thick but still very fluid like.
So long story short, For my climate where in the winter it can get to the low teens/ single digits is this a problem? When I leave my neighborhood it's a quarter mile to the highway then it's 65-70 mph. Can this actually cause damage? How long does it take gear oil to thin out? I'd really like to stay with a mineral oil if possible. Would an 80w90 be adequate or too thin for the 4.56s ? I don't tow much but for what's its worth in the summer the diff gets really hot to the touch!
One thing I've noticed is that Lucas 85w140 seems to have a really low pour point. Almost to the point that it seems like it's a mis print at -27f. The Mobil is supposedly good down to 0 but it didn't flow at all in the cup.
Thoughts? Am I overthinking this? If the Lucas does really flow that much better I may try it.
Thanks in advance!!
I have a 2013 F150 ecoboost that originally came with an open 3.31 rear. I eventually ditched the stock wheels and tires and put some 35" Nitto Trail Grapplers which absolutely killed the power in the truck. I then swapped to 4.56 gears and added a Detroit true trac in the rear. I know Eaton recommends a mineral based oil but allows a synthetic preferably without friction modifiers.
The place I had the rears done absolutely recommended a mineral oil and never a synthetic. I did the break in for 500 miles with Mobilube HD 85w140. Dumped it and refilled with the same. It's been in there now for about 20k miles. No problems or weird noises.
Just for kicks I took some of the Mobil 85w140 and put it in the freezer overnight in a solo cup. It had nearly turned solid!! I turned the cup upside down and it didn't flow at all. The freezer temp is set to zero degrees. I did the same test with Mobil 1 75w140 I had laying around and it was thick but still very fluid like.
So long story short, For my climate where in the winter it can get to the low teens/ single digits is this a problem? When I leave my neighborhood it's a quarter mile to the highway then it's 65-70 mph. Can this actually cause damage? How long does it take gear oil to thin out? I'd really like to stay with a mineral oil if possible. Would an 80w90 be adequate or too thin for the 4.56s ? I don't tow much but for what's its worth in the summer the diff gets really hot to the touch!
One thing I've noticed is that Lucas 85w140 seems to have a really low pour point. Almost to the point that it seems like it's a mis print at -27f. The Mobil is supposedly good down to 0 but it didn't flow at all in the cup.
Thoughts? Am I overthinking this? If the Lucas does really flow that much better I may try it.
Thanks in advance!!