Hey everyone,
I was in a shop today wtih a friend and asked a mechanic about synthetic oil. Basically he didnt tell me anything out of the blue but he said if i want to switch to synthetic oil, I have to first clean the engine from old oil and stuff by doing a engine flush. Are there any negatives to doing that. For example, a transmission flush might kill your tranny, how about engine flush. I have 98 xlt 4.0 with 137K miles.

Hey everyone,
I was in a shop today wtih a friend and asked a mechanic about synthetic oil. Basically he didnt tell me anything out of the blue but he said if i want to switch to synthetic oil, I have to first clean the engine from old oil and stuff by doing a engine flush. Are there any negatives to doing that. For example, a transmission flush might kill your tranny, how about engine flush. I have 98 xlt 4.0 with 137K miles.

Well I don't know about an engine flush. But I switched to a synthetic at like 40,000 miles and had no problem. But I have been told that switching to a synthetic after 75,000 miles will cause problems because of worn seals and such. If I were you I think I would try a synthetic blend for vehicles over 75,000 miles. Hope this helps.