Switching to synthetic

I have a 98 3.8L with about 90k miles.

I've been wondering if switching to Mobil 1 would help extended the life of the van. I've heard that an older engine shouldn't be switched over.

Same question about switching tranny fluid to synthetic.

Engine runs good now, only problem is an intermittent IMRC stuck open, banks 1 & 2 (1537 & 1538 if I recall correctly,) which I haven't gotten around to checking out.

Thanks

I posted a long rant about the IMRC issue last night in another thread......give it a read....as I would be repeating myself.....The person had non-operative IMRC. It is possible that you have a leak developing in one of the IMRC actuators.......which would weaken the vaccum to both actuators....

Synthetic. I have been using Mobil 1 synthetic since just under 38K miles. I am at 153+K miles now. Inside the engine is very clean, I use very little....if any oil. I would recommend the switch. People have concerns about the engine leaking oil.....I would not be concerned. Try 2 change intervals.....as it may take that long for the engine to "adapt" to the new type of oil. I have found that the Mobil 1 oil provides MUCH better cold starts / lubrication versus conventional oil of the same grade.
Mobil 1 can be bought in 5 quart jugs at Wal-mart for about $17 for the normal Mobil 1 and for $23 for the new "EP" Mobil 1.
I do NOT go the extended oil change interval.....so either one is fine for me....problem with extended oil change interval (and this is only my opinion) is that....even though the oil may hold up......the filter would need to be changed anyhow......

Take a look down inside the oil add cap hole in the front valve cover.....if it is free from sludge (which I am guessing it is)....then you should have NO problems. If you do have some sludge.....then do the switch to synthetic.....and then change again with synthetic and a quality oil filter to get the initial cleanup of sludge out.
You do NOT need to add any additives.....the Mobil 1 seems to have a very robust detergent package.

For the tranny......you MUST use Mercon V (not Mercon) which....I think is already a synthetic. You MUST change the tranny fluid at LEAST every 30K miles.....21K miles for "severe" service. This is a must for keeping your tranny away from expensive repairs. I also have a nice big auxilary transmission fluid cooler. Also....remember that the Windstar has a CAR transmission.....NOT a truck transmission. It is NOT up to any heavy duty towing. I learned that the hard way.

Thanks for the advice,

I've been reading a lot of the threads on this site, and it is very helpful. I'm glad I found this site.

I changed the transmission fluid about 15k miles ago. Thinking back, I think all the Mercon V that I saw was synthetic.

I too use mobil 1 oil.. I like it.. as for the tranny I use mercon V. Dont like it but you must keep it changed like mentioned above. I had to change mine again after 15,000 miles. It was dirty.. Now I do use mobil 5000 now but prefer mobil tri synthetic. just had a sale on mobil 5000 that week.