Does the ICE stay lubed?

Prius, ever since that first model back in 1997, has always taken the same approach... spin the engine up to idle speed, wait for oil-pressure to be established, then squirt & spark. That circulation will take place. There is nothing to be concerned about. Just drive it.

 

I think Toyota's upcoming "Dynamic Force" engine is supposed to have an electric oil pump. That could pre-oil it before it starts moving.

 

Oil will cling to the engine internal surfaces for a very long time. Don't worry. Think in terms of months. I've had a truck parked for 5 months while I was away working. No problem. Engines in dealership back lots, machinery rental yards, heavy equipment in the winter, ski run grooming machines all summer, as well as the emergency generator engines on ski lifts all summer and most of the winter. Many boaters have their engines shut down for months. No problem remaining shut down, then they start when needed with no problem.

 

Even when you have 30 miles of electric, and are going downhill for the first few miles the ice starts after a few minutes and runs for a few minutes.

 

What he said. The oil will cling for a long time. And the Prius starts the engine very gently, making sure oil pressure is up before combustion puts a load on the bearings.

 

All that said, it is a good idea to periodically run the engine under load for several minutes after it reaches full operating temperature. If you wanted to run, say, a half-hour drive using gasoline, that's always a good idea to keep the machinery in good condition. The gasoline needs to be consumed and refreshed periodically, also.

 

I think you may be confusing Prius and Prius Prime. You can, in normal circumstances, drive the whole EV range without ICE turning on.

 

Most oils include a small amount of MoS2 (molybdenum-disulfide) in the oil as an additive. This material clings to metal wear parts even when oil drains down to the pan. Because MoS2 is a dark grey and makes the oil look dark, very little is used to maintain the oil's light amber color when new.

I use Liqui-Moly to fortify the original oil. I used to add 4 ounces, but have found 2 ounces to be sufficient for the four cylinder Prius.

The Germans, who make this stuff swear by in in Porsches, Mercedes and BMW's. At $7 for an 8 ounce can, it's really cheap insurance.

 

A concern with any aftermarket oil additive is in the risk in thinning out the oil's additive package.

 

No, it doesn't thin the oil. MoS2 is composed of micron sized solids. When cleaning the oil drain pan, it's the last stuff to come off when using a degreasing solvent.

 

I'm not aware of any oils that use MoS2 in motor oil. It is not well suited for that. Many oil makers add a liquid oil-soluble moly compound, molybdenum dialkyldithiocarbamate or a similar compound. In conjunction with the zinc dialkyldithiophosphate or similar compound they plate an extremely thin, hard, low friction surface on the metal surface. As an alternative that gives very similar results, some oil makers use a titantium compound in the place of the moly compound.

 

Risky. That's been an option for engine designers for a long time, but it is nearly never done because of the massive consequences were the pump to fail. A mechanical pump directly driven by the crank has proven to be a safer choice.

Perhaps they decided it was OK because the engine is under the complete control of the hybrid computer, and the ICE can be disabled by the computer if a pump failure is detected?

There are some energy savings to be had by using an electric oil pump. Very often a traditional oil pump is pulling several horsepower from the crank, and often it is supplying much more flow and pressure than is actually required.

 

I agree. A mechanical oil pump seldom fails. In air conditioning, power steering, and cooling, there may be a period of seconds, before failure causes irreparable damage, not with lack of oil.

 

I think the scenario the poster is referring to is that you are starting out with a full battery at the top of a hill. When going down the hill, there is no place to put the regenerative energy, so engine braking is used, which requires the engine to go through its warmup cycle.

 

I wasn't referring to the viscosity, though it could be affected. I was talking about watering down the essential additives in the oil; the detergents, viscosity modifiers, and mainly the acid neutralizers. Dilute them down, and the oil may not provide full protection for the expected life. Oil does more than simply lube parts.

I wouldn't worry about 2 ounces in a change, but some additives call for more.

I would worry about the sulfur. Oil does get burned, and sulfur is bad for cat. More importantly, the water that gets into the oil can react with it, and form sulfuric acid. Acids are always forming in running motor oil. It is why there are neutralizers in it.

The system is also fully capable of spinning up the engine with M/G1 for braking without burning fuel. This will circulate oil through the engine.

 

My understanding is that whenever the engine is turned for any reason, be it no-fuel engine braking or the need for it to provide power, that it is programmed to first go through a warmup cycle. I could be wrong, but that is what I always heard.

 

I live at 1480’ and drive 10 miles downhill with my prime, it comes on in the first ten minutes for a cycle, every time, no confusion.

 

What oil do you use and where do you get it serviced?

 

I think what the poster above is talking about is Liqui Moly Mos2 or even Liqui Moly CeraTec, you can add it yourself. I run it in my BMW and I use 5w-30 Castrol Synthetic.

The Prius Prime runs 0w-20 Toyota Synthetic which is an excellent oil. There is absolutely no reason to run Liqui Moly additives in a Prius, it was designed for engines that operate under harsh conditions (track, spirited driving) like the BMW M3 or M5 (6-8000 RPM). Here is a link to buy it online if you are interested.
MoS2 Anti-Friction Engine Treatment (300ml Can) - Liqui Moly LM2009 | FCP Euro