brianinca
Well-Known Member
The oil is going somewhere for the first few thousand miles. Say what you will, tolerances are engineered in, and the wearing in period may not require different behavior in some cases, but it is there regardless.
My wife was just teasing last night about manually calculating mileage every fill up on my gas JTR. At 13K I started seeing a 1 MPG improvement (~6%). It certainly wasn't from a change in driving style. Full synthetic is very effective lubrication, so break in is slower.
Back in the day, I put full synthetic in my Ford Ranger with a 60's tech German V6 from Ford Germany (pushrod). I pulled the trigger too soon (500 miles) and when it finally hit 21K the mileage jumped a solid 1.5 MPG (+14%) (. I waited until 1K to do the same with a 98 Ford with the OHC version of that motor, it broke in at 8K and gave me ~2 MPG more (nearly 20%). I gave that truck to my gardener's son this summer, 198K and still getting the same mileage, 14 MPG in town.
For sure the difference in tolerances in modern engines plays a role in reducing the impact of break-in, and I've had vehicles that didn't show a mileage improvement (2006 H2 for example) but it remains a thing. Ford switched to full synthetic gear oil for rear axles in that 98 Ford from 97, that was all for a .15 MPG improvement. Synthetic lubricants reduce friction & wear in ADDITION to more precise tolerances and better materials.
My wife was just teasing last night about manually calculating mileage every fill up on my gas JTR. At 13K I started seeing a 1 MPG improvement (~6%). It certainly wasn't from a change in driving style. Full synthetic is very effective lubrication, so break in is slower.
Back in the day, I put full synthetic in my Ford Ranger with a 60's tech German V6 from Ford Germany (pushrod). I pulled the trigger too soon (500 miles) and when it finally hit 21K the mileage jumped a solid 1.5 MPG (+14%) (. I waited until 1K to do the same with a 98 Ford with the OHC version of that motor, it broke in at 8K and gave me ~2 MPG more (nearly 20%). I gave that truck to my gardener's son this summer, 198K and still getting the same mileage, 14 MPG in town.
For sure the difference in tolerances in modern engines plays a role in reducing the impact of break-in, and I've had vehicles that didn't show a mileage improvement (2006 H2 for example) but it remains a thing. Ford switched to full synthetic gear oil for rear axles in that 98 Ford from 97, that was all for a .15 MPG improvement. Synthetic lubricants reduce friction & wear in ADDITION to more precise tolerances and better materials.
I not saying you shouldn’t take it easy during the first miles, I am saying there will be no noticeable difference in power or mileage after the initial period. Engines today are made with very precise tolerances and from materials that do not wear in significantly.
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