OK so I have been overprotective on the change interval at the outset of breaking in this engine..using full synthetic at the first 1000 recomended, 2nd at 3k, and now am thinking 5k as it is right at the 155k mark on the odometer, whats normal on synthetic ?

 

Given that Ford now is using 7500 mile intervals on regular syn blend Motorcraft, I'd go with 4-5000 on syn blend and 6000-7500 on full synthetic. This is after a 40 year habit of 3k oil changes. I've switch 2 of our vehicles to full syn, and it's hard going that long, but I feel more than safe.

If you are really working the engine hard, maybe go a bit earlier on changes. If you're nervous, try an oil analysis someday.

George

 

I always changed my 5.4L every 5K with semi syn Motorcraft 5w20. Never used a drop, never got black. Always use a Motorcraft filter!!