Originally Posted by lucky55616
I have a Sunseeker 3010DS on a 2014 Ford E450 chassis with 2,700 miles on the odometer. On my last oil change I had 5W-20 full synthetic put in instead of the semi-synthetic blend. When I brought the motorhome into a Ford dealer because the check engine light was on, I mentioned to the service manager that I recently had the oil changed and went with full synthetic. He said I should not have done that because the 6.8 V10 will burn a quart of full synthetic every 1,000 miles as blowby and that once you put full synthetic in the engine you can never go back to the semi synthetic blend. I have never heard of that before and the Ford manual recommends either the semi synthetic blend or full synthetic. Has anyone else started using full synthetic and did you have any problems with the engine after you started using it ?
No, you shouldn't have a quart of blowby.
As for going back to regular motor oil, I've heard this before on radio auto "repair" shows and it was by people that really, REALLY should know.
As for blended motor oil: The blend is whatever the manufacturer wants to make it. Some reportedly use as little as 5% of synthetic oil and some use up to 20%. I haven't heard of more than that but there could be brands that do. I use full synthetic oil in my cars. I don't use it in my truck as putting 14 quarts get pretty expensive but I change that oil a LOT sooner.