I’ve heard some where that the 2015…..was changed and does not have oil consumption and head gasket problem that the other gen3’s have …does anyone know if this is true ?
Partway through model year 2014 Toyota revised the pistons and rings. This has hopefully reduced oil consumption issues. At some point the EGR system had a revision to the valve component, and there was a software tweak as well. There was also an intake manifold change, or changes. I doubt any of that had much if any effect on the head gasket failures. Appreciable improvement came with gen 4, with its completely revamped EGR system. however early 4th gen years were prone to coolant leaks in the exhaust heat recovery system, which if left unattended long enough could also cause head gasket failure.
take a peek inside the egr tube to see how much junk is in there, and if it needs to be cleaned. haven't read about too many 2015 head gaskets if any, but only time will tell. still, it has much better engineering than older gen 3
If a 2015 has no oil consumption in 5k miles, it is unlikely to clog the egr and intake systems. The updated egr valve will be on it by then; it's possible it does not have the latest ecu software. The head gaskets were revised but they were not in the 2015 production run. A new hg part from Toyota will be the revised gasket. The gen4 engine redesign was significant and went beyond a new egr cooler placed after the cats for dramatically reduced carbon buildup under any condition. Cylinder wall cooling was redesigned to even wall temps from top to bottom along with a special foam and metal insert. This design is still used in new 1.8L Toyota cars even though a gen5 2.0L engine is the primary power plant in most Corollas and Prii. This 2021 post details the gen4 redesign Did 4th Gen fix 3rd Gen? | PriusChat Interestingly, Hybrid Pit now sells a gen4 block with the cylinder cooling improvements mated to a gen3 head and egr system to ensure mechanical and electrical connectivity when installed in a gen3. They are claiming gen4 reliability. In the end, you might face an engine replacement or other major expense even in a well kept 2015. It is just not as certain as the 2010- mid 2014 models.
I said unlikely to clog, not saying it won't put a light coating on the system. No clogs, no problems. You have to see a few dozen high mile oil burners vs the occasional high mile good gen3 engine to know this. You get heavy carbon buildup when oil burning since it hits the egr system before the cats can burn it off. No oil burning means functional egr and clean cats. Which is why Toyota changed gen4 egr pickups to after the cat.
