2010 Prius - oil change - synthetic or semi-synthetic

I vote for full synthetic. Even if it is more, it lasts twice as long and it does not break down at all. Even though it's 3x as much, you can go twice as long without changing it. I do my own oil changes and have only used full synthetic and change at 10k.

 

2010 is an oil burning candidate. if you want to keep it running, i would treat it with tlc, and add the extra egr and intake cleaning as well.

 

most are doing 10k synthetic, but some are doing 5k, hoping to save their head gasket.

 

I use semi but change at 4000 miles

 

I'm doing my own synthetic changes at 10K using Mobil 1 since ToyotaCare ran out. It's less than twice the price of a good conventional oil at Wal*Mart. Only at 43K total miles so no hint of any oil consumption yet.

@bisco, not sure how oil changes will save a head gasket. I always thought their durability was a function of design and how many temperature cycles (causing the metal to expand and contract) they had to go through, plus any severe situations such as pinging or overheating.

 

me neither. it is unclear exactly what the problem is, but some claim that 5k oil changes prevent oil burning, which is a precursor to the head gasket issue.

 

I'm one who preaches 5k oil oci's with full synthetic, but strictly as a means to prevent, or at least delay the oil control ring coking which causes the oil consumption in these engines. My theory is that due to the relatively high volatility of the 0w-20s and even a lot of the full syn 5-30s, they can't tolerate the 10k miles interval without burning onto the control rings. I think combustion temps are high due to the ever increasing thermal efficiency Toyota is wringing out of these engines. I also don't believe Toyota intended for these engines to run 10k miles intervals on North American 0w-20s and that gubment/CAFE forced it. @Mendel Leisk , what's the oci your Canadian owners manual recommends?.. If I'm recalling correctly, it's well less than 10k miles. That's an entire paragraph of unsubstantiated opinion..

Oil burning in and of itself is not causing head gasket issues. However, it's very likely that oil burning does speed up the rate at which the EGR circuit clogs, and it is the clogged EGR circuit (or the massive heat generated in the top end due to it) which is behind the blown head gaskets. So an oil burning turd gen can probably keep it's head gasket intact indefinitely, so long as the EGR circuit is kept clear. But for an owner with no idea what's going on, oil burning will likely lead to a blown head gasket sooner than if not oil burning.

 

Since Toyota recommends Full synthetic for the Gen. 3 I think it unwise to not use it.

 

It's 8000 kms (5000 miles) or 6 months, for all Toyota vehicles. As of 2016 I think they've gone to 16K kms (10K miles) or 12 months though. I would stick with the 8000 kms or 6 months myself though.

I don't believe they say anything about synthetic, vs conventional oil. By spec'ing 0W20 they are sorta inferring it, but yeah, that's all. Is there a semi-synth 0W20?

I like Toyota 0W20, it's full synthetic, and pretty cheap through my dealership.

 

There are a few semi-syn 0w20s now but when turd gen rolled out they were all full syn. I think tankyuong's 4k semi-syn is fine or even 3k on a good conventional. Any decent motor oil can do the job so long as it's not abused.

Gen 2 had a similar issues with 5k oci's on conventional. 3k conventional or 5k full syn might have made for less oil burning issues there, too.

 

Last sentence is your answer. To keep it going for that many more miles, you avoid semi.

 

Mobil 1 Annual Protection in our v, with corresponding filter denoted with part number ending in "A". Ready for anything thrown it's way, for 1 yr that is, (since we don't get anywhere close to 20k miles in a year).

 

Which filter did you go with M1 AP?

 

Mobil has extended performance filter. The old part number has no "A" at the end, box says good to 15k miles. The ones with "A" have 20k mile rating. http://www.mobiloil.com can give you the correct filter. I ordered from Advance Auto online, but Walmart may have them as well. I think the older one still in stock at certain stores, at least last year when I started using it...

 

It will be very interesting to see how Mobil deals with their warranty if a Prius starts consuming oil while using their best oil. (I'm afraid we may be very far from that day at about 19k miles).

But I can tell you I have done my homework on oils, and the TBN that Amsoil rates 25k mile oil is the same TBN Mobil uses for 10k mile oil (0W-40 FS). Mobil has not disclosed the TBN for it's Annual Protection last time I checked, but they have run the oil for 20k mile intervals for I think 120k miles and teared down, engine looks new....

 

I would not mind doing 5k oil changes but Toyota cheap out on filter design and its a real pain to do oil changes myself so 10k is much better for me with full synthetic.

 

I'd expect the peak combustion temperature in a Prius (or any Atkinson type engine) to be about the same or lower than in a conventional naturally aspirated engine. The efficiency comes from having a higher expansion ratio than compression ratio, not from having higher pressures and temperatures.

My theory would be that it's not actually the oil burning that's causing deposits, but the contaminants in the oil (mostly trace amounts of fuel blowing by the rings) that cause the deposits. The Prius would be especially vulnerable to this, as the ICE can shut off a lot in low speed driving so it takes a while for it to get up to full temperature if it ever does. Then when you do get onto a highway and go up a steep hill, you've got a relatively small engine for the size of car so it's working really hard and that bakes the contaminants into deposits. That's my unsubstantiated conjecture and I'm sticking to it until somebody comes up with a better sounding story

Bonus theory: Using B mode occasionally can help because it would be the only time the ICE is operating under high vacuum conditions which will increase oil flow through those little holes in the piston that tend to clog, giving them a chance to flush out deposits before they become permanent.

 

If you drive less than or about 10k miles a year this fits fine with synthetic. If you drive 20k miles in a year go with the Mobil 1 AP. No matter what you use 1 yr is the limit...