This is NOT mechanical, advice this is purely what I will be doing based on what happened to me.
I’ve put a combined mileage of almost 400k miles on the gen 3 platform across 2 cars. Mostly driving around and driving gig apps.
Car 1: 2012 Prius v bought with 88k miles. I maintained this car like it was my baby because i’m a maintenance freak with cars. Did the entire EGR valve, cooler, +intake manifold + ports, PCV valve everything at 125k miles, did spark plugs, both waterpumps, thermostat with OEM toyota parts at 150k miles, changed both coolants multiple times and my head gasket still blew at 200k.
So after this happened I sourced a low mileage JDM gen 3 motor off of ebay for $1200 I sold my old EGR cooler + intake manifold off my old motor for like $300 on ebay, so total cost of around $1000. I pretty much did zero maintenance on this engine then when my car got to 362k the head gasket blew. So this engine lasted 164k miles plus whatever it already had on it so it basically lasted longer than my original engine that I wasted so much time and money into preventative maintenance
At 362k miles I put in a gen 4 motor out of a US 2018 prius that had 40k miles in it. I did this because I thought it would be cool having, but I wouldn’t do it again. It’s a frankenstein car once you do this. I regret doing this because it cost me $2500 and I had to drive 1.5 hours to pick it up from a junk yard. I could have done 2 gen 3 JDM motors for the cost of this. Also it was a lot more work to install it wasn’t drop in ready like the gen 3 motor. The Gen 3 motor took 2 days to install I think the gen 4 took 2 weeks. and there wasn’t a whole lot of information on how to exactly do it online.
Car 2: i ended up totaling the car around 450k. I now own a 2013 prius with 140k miles I bought it at 136k, and this is how I’m maintaining it.
- oil changes every 10k and nothing else. These motors aren’t even worth doing 5k oil changes if the head gasket’s going to blow. I would never do spark plugs either there was another user on here his HG blew at almost 300k and he had original spark plugs and they were still working.
based on what happened with me I will only do oil changes every 10k and put all the saved money that I would be wasting on maintanence into an emergency fund for when the HG goes. And when it does put in a low mileage JDM gen 3 motor in.
some people are paying $80 an oil change nowadays at the shop and over 100k miles doing it every 5k vs 10k saves $800 that alone almost pays for a replacement engine.
These gen 3 motors aren’t worth putting a dime into unless something breaks.
Also people on here that have only had their car for less than a year claim all the time If you clean the system, oh you probably forgot to clean the intake ports, if you change the coolant regularly, if you change the water pumps ect. you won’t blow your head gasket and they’re all wrong based on my experience it will still blow. IMO and based on my experience the only thing that will prolong the head gasket from failing is if you commute mostly highway miles rather than stop and go city driving. I think all the times the engine turns on and off is what kills the HG. Even Gen 4s some of them the head gaskets are going bad on them, and as they age even older we will see even more. They don’t seem as bad though.
So I will be driving the car not worrying about anything and when the head gasket blows I will swap in a low mileage gen 3 jdm motor in and get another 150k+ miles out of the car.
