Ok, I have been convinced to switch to synthetic oil. My Ford F-150 has 125k miles on it. Can I switch to synthetic oil in it? I have heard that higher mileage engines will leak like a sieve when switched over. Do I need to do an engine flush, one without Kerosene in it, prior to the switch? Please enlighten this novice synthetic pupil with your wisdom.

It would be interesting and perhaps helpful to hear your reasons for going synthetic. I just switched wife's 100,000 mile minivan to Vaovoline Synpower from synthetic blend, mostly to see if it handles better the short trip effect (about 4000 to 5000 miles total in a year). Unless your vehicle has oil leaks, I would not be too concerned. Might ease in with a blend or a Group III synthetic before going full synthetic. Maxlife synthetic is specifically made for high mileage engines and might be the best deal if leakage is a concern, but modern synthetics should not cause leaks.

As for cleaning the engine, maybe not a bad idea. The synthetic likely will do some cleaning and that may shorten your first synthetic OCI, which is maybe OK. Alternately, you could run a product like Auto-Rx.com or try Schaeffer's Neutra 131 ( http://www.schaefferoil.com/datapdf/131.pdf ), a fuel conditioner that also works (in much shorter time than Auto Rx--maybe 500 miles tops) as a crankcase purge (I believe I saw Schaffer's had an ad in Noria's Machinery Lubrication Magazine) . I am runing the Auto Rx now but it's too soon to know how it works. Haven't used the Neutra but others have had good results. With Neutra you could run the purge the last 500 miles, refill with a cheap filter and cheap oil for a short time (10 - 100 miles maybe), dump that and put the synthetic in.

I would not switch with that high mileage. The engine has seen to many miles on petroleum and has likely accumulated a lot of engine deposits. Gr. IV PAO Synthetic oils (Amsoil, Mobil 1 etc) are inherently detergent so the oil additives are going to be used up fast and may require frequent changes. A tell-tale sign will be oil consumption. I would continue to use what you have been and when you get a new vehicle, switch to synthetic at the first oil change.

If anything I would use the Group III synthetics ((dino-syn blends)) which are most everything but Amsoil, Mobil 1, Red Line and maybe a few others which are Gr. IV (100% synthetic),(((these companies also market Gr. III oils))). Big oil brands like Castrol, QS, Pennzoil and other on-the-shelf oils fround at Walmart are GR III

I have used synthetic oils and lubes exclusively since 1977 in everything. I would not use anything else. I purchased a new GMC Ext Cab Z71 pickup this year and have everything but the PS and transfer case running synthetic and all done is less than 10,000 miles with the ATF being the last thing done.


btw - I have always used Amsoil

This message has been edited. Last edited by: MikeR,

Change to Synth covered in Question archieve


http://www.mobil1.com/index.jsp

Its interesting that an earlier answer was not to change and a later answer it was OK, mayber from tri syn to super syn.

I agree it is a risk but TallPaul has info on switch to High Mileage and quality minerals are cleaner as well.

There is also Castrol Start Up with esters, a half way house.

Pete I know of a 172k Ford 281ci motor that was changed to Mobil Synthetic two years ago . Those were the miles at the time . No leaks !

My own Ford V-8 was switched around 1.5 years ago w/o problems . It is more of a viscosity issue than anything . If you change and it seeps first interval I'd say go ahead and run a second interval to see if it stops .

Mobil has hi-mileage oils that pump very well in the winter which are a good option . These can go up to around 7500 miles in many engines .

It's interesting to note that seal compatibility problems haven't been raised. I know it's not so much of an issue with modern synthetics but it is still a concern.
Personally, I can't speak highly enough of syn oil but the research needs to be done before the change is made. I have three cars and run synthetic in only two of them because I can't justify the higher running costs for a car that already has regular changes on mineral.
As far as switching goes. If you know you are going to get the benefits from it then an engine flush is obviously preferable. But it is a bit of a debate between professionals as to which is best. Some say a shorter oil change interval between the first 3 - 4 change outs while others say that there is no need at all. Personally, I believe it once again comes down to what is going to be cost effective and give you the best long term benefits. With my Toyota Supra I did an engine flush and with my Nissan Skyline I used shortened change intervals.
I strongly believe that each situation should be evaluated independantly as in my experience, there is never a common solution to a general problem.

Seal compatibility appears to be a problem with early Synthetics which have noe been solved.

Hovever the mineral oil crud could prevent leaks showing, wheras the cleaning power of Synthetics identify the problem, so its not the fault of Synthetic oil.

On basis of regular oil changes with good quality Minerals, should there be a build up of crud to worry about, or are minerals still a problem in this area despite regular chances.

I would stray from using Kero as a flushing agent in your engine and use a good flushing agent!
I'd say switch to a syn oil if you feel. But run a higher viscosity if she's leaking (or get the seals replaced).