What is a good break in oil for a 4.0l?

[black_demon69]

Just curious

 

[Dirtman]

I always just used conventional oil of the spec weight for break in. The lower detergent level doesn't wash the assembly lube out as quickly. Proper priming and break in procedure matters more than the oil type though in my opinion. Replace at 500 miles then run it like normal.

 

[RonD]

I always ran a name brand but cheap straight 30w then change it to my regular 10w30 after 500-600 miles

Newer engine materials don't really need much "break in" like the older materials did

 

[97RangerXLT]

Break in oil for a 4.0? aren't most 4.0's (even the SOHC ones) already broken in?

AJ

 

[black_demon69]

Mine won't be currently getting block machined????

 

[sgtsandman]

I would just run with whatever the manual recommends unless the machine company has a suggestion. I know some vehicle manufacturers have a break in oil they put in during assembly but I have no idea if the average person can get that or the additives they use. I think the above suggestion of changing out the oil and filter after 500 miles might be a good one.