NEED HELP ON THE NEXT 100000 Miles

[alabama kayak bob]

Just joined your forum. I have a 2000 Four Runner with 200,000 miles on it runs fantastic changed the oil every three thousand miles or so. Now should I convert over to a different high mileage oil if so what would you recommend or stay with the stock stuff I have been using at the oil change shops.?
Next, I have done nothing to the transmission and wondered would it hurt to do a BG treatment and have the transmission oil changed using this method? Should I do nothing and not change the old oil?

If the engine should ever need a overall say at 275,000 miles and beyond would you replace the engin with a earlier model say with50k miles on it from say a totalized out four runner and then have it put in the old car. Or would you rebuild the engine I have had in it which came from the factory.

Also how about the transmission if she goes would you rebuild the old one or purchase a newer model that got in a wreck ?

Next and last question can you put a five year old transmission or engine in a 2000 four runner will they fit? Many times you can find and great car that got totaled out and the engine and transmission are still working fine. I have a repair shop who the owner is 18 years certified Toyota man so I got the right guy to keep me going. Look forward to your advice into the future bob

 

[BucknutBob]

You seem to have a lot of worries about things that you don't need to worry about, friend. Why all the concern about replacing engines and transmissions that are working fine? The high-mileage oil certainly wouldn't hurt, but if you've been keeping regular changes for quite some time, then the regular oil should suffice, especially is you're not noticing any oil loss between changes. Now you have to be careful with the transmission, though--if it has never had regular servicing of the fluid and filter, you risk breaking loose the varnish that has built up on the internal parts, which can damage it down the road. Yes, you should get new fluid in there if it hasn't been done in ages, just be aware of possible hiccups. Maybe do the cleaning, run the new fluid for a short while, and clean it again. Your certified Toyota man should have solid advice on that matter. As for replacing the engine or trans, why concern yourself--when the time comes, then you can deal with it.