Bought Used Gen3 2010 Prius IV @ 155k miles. What should be done?

Do you have any repair history on this car? You can run a carfax to see if there are repairs/maintenance that has already been done, so you don't have to repeat them. 155k miles, many things should have been done already

 

Yes, for engine water pump replacement. Also, be prepared for the head gasket going bad in the next 10k to 45k miles.

 

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The top two links in my signature are EGR related (on a phone turn it landscape to see signatures). Also recently added an EGR cleaning workflow, here.

At your miles, I wouldn’t look at EGR cleaning as a “get out of jail for free” card; it’s late in the day to start with this. Unfortunately, it’s just about the time head gaskets start letting go, so tread cautiously, don’t make any major investments in it for the next few months; just deal with the EGR, then wait and see for a bit.

 

B12 or other piston soaks won’t help a gen3 Prius burning oil because of their low tension piston ring design flaw. Save your money for a rainy day fund.

Try to avoid dealer repairs. Sometimes their diagnostics are ok but their repair costs are often 150-200% higher. Do find and use an independent hybrid shop before you need it. 5k mile oil and 50k mile coolant changes are your best bet.

 

At 155k miles, I would go for the full works. Try to get parts from the dealership or rockauto. Ebay has a lot of fake parts

1. plugs
2. pcv valve
3. change coolant
4. change transaxle oil
5. change brake fluid and check brakes
6. change water pump (you can get away with changing the rotor only or if you want to splurge change the pump using OEM pump)
7. clean throttle body
8. clean entire EGR circuit

I wouldn't overly invest too much money on this car. Since it's burning a lot of oil and it's nearing it's head gasket replacement time (anytime over 150k miles). I would just do simple basic needed maintenance.

 

2. PCV valve is easy and it could be part of the reason why you're burning so much oil. You would normally do this along with the EGR circuit clean, the removing of the intake manifold would expose the location of the PCV valve.
4. Transaxle fluid - this is not urgent since Toyota considers this to be a lifetime fluid. But we all know there is no such thing as a lifetime fluid.

I would tackle the water pump, throttle body cleaning, and EGR circuit at the same time. The water pump is actually very important to change out as it could fail and you could end up with an overheat condition that ultimately leads to (contributes to) a head gasket failure. Since you've already changed your coolant, you would just drain and fill that coolant back into your system during the water pump change.

The bad news hasn't really been shared with you yet. These cars tend to have 3 big failures. 1. Brake booster pump, 2 Head Gasket, 3 HV battery. Any of those 3 items will cause you some big problems and are big ticket items. So hopefully you can put away some money in anticipation for when those repairs are needed.