If were to replace the rings on an engine ...how difficult is it if it is a 3.0 V6 Toyota engine?

[?Tao?]

what tools would i need? and how time consuming?
and how much longer would prolong the life of the engine?
and how much longer would prolong the life of the engine?

[Semtex]

As with any engine replacing the rings means completely dismantling the engine. By the time that you've removed the engine and stripped it down you may as well consider sending the block off for reboring and then buy new oversized pistons and rings. The crank should be ground and undersized shell bearings fitted. Have the valves in the head replaced and fit a new oil pump and it'll be as good as it was when it left the factory when it was brand new. If the rings are completely worn out then you're not going to get a lot more life from a new set if that's all you change.

If you're not prepared to do all that then it would be easier to fit a second hand engine from a scrap yard from a lower mileage car. This can easily be done in a day with a socket set, combination spanners, a jack, screwdrivers and some sort of lifting gear - even a good block and tackle attached to a tree will do (I changed an engine for someone this way in a car park in France as there was no other option)

[Semtex]

As with any engine replacing the rings means completely dismantling the engine. By the time that you've removed the engine and stripped it down you may as well consider sending the block off for reboring and then buy new oversized pistons and rings. The crank should be ground and undersized shell bearings fitted. Have the valves in the head replaced and fit a new oil pump and it'll be as good as it was when it left the factory when it was brand new. If the rings are completely worn out then you're not going to get a lot more life from a new set if that's all you change.

If you're not prepared to do all that then it would be easier to fit a second hand engine from a scrap yard from a lower mileage car. This can easily be done in a day with a socket set, combination spanners, a jack, screwdrivers and some sort of lifting gear - even a good block and tackle attached to a tree will do (I changed an engine for someone this way in a car park in France as there was no other option)

[Semtex]

As with any engine replacing the rings means completely dismantling the engine. By the time that you've removed the engine and stripped it down you may as well consider sending the block off for reboring and then buy new oversized pistons and rings. The crank should be ground and undersized shell bearings fitted. Have the valves in the head replaced and fit a new oil pump and it'll be as good as it was when it left the factory when it was brand new. If the rings are completely worn out then you're not going to get a lot more life from a new set if that's all you change.

If you're not prepared to do all that then it would be easier to fit a second hand engine from a scrap yard from a lower mileage car. This can easily be done in a day with a socket set, combination spanners, a jack, screwdrivers and some sort of lifting gear - even a good block and tackle attached to a tree will do (I changed an engine for someone this way in a car park in France as there was no other option)

You can do it but it probably isn't worth it for a common Toyota. You need to pull the engine out of the car, remove the heads, and oil pan at a bare minimum to get the pistons out. At that point you might as well remove the crank and send both it and the block to be machined.

To put it back together you need an engine hoist, torque wrench, ring compressor/mad skills, and basic hand tools. You will need to buy new pistons, bearings, rings, gaskets and you will want a new oil pump.

If you only replace the rings you might get 10,000-20,000 miles before you're doing it again. At that point you might as well keep running it how it is and run thicker oil. You are much better off doing a real rebuild.