It Turns Out, Hybrids Are Really Hard On Engines

Hybrid vehicles are uniquely challenging due to the frequent engine start/stops, as well as lower overall engine temperatures, which can lead to water and fuel dilution.

Hybrid vehicles are a great solution to improving fuel economy, but they have their own unique challenges. Because hybrid engines start & stop frequently, this often results in lower engine temperatures, which in turn can create issues with water and fuel dilution. Frequent start/stops, water, and fuel, can all create problems that exacerbate engine wear.

To combat this, Mobil 1 has developed Mobil 1 hybrid, a full synthetic motor oil that is designed to meet the challenges that hybrid vehicles place on engines. This video will focus on three main subjects: how hybrids work, why hybrids are hard on engines, and what solutions exist to combat these challenges.

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[EngineeringExplained]

**Let's address the common questions!**
*1) Does this mean hybrids aren't reliable?* No! Just because something is challenging or problematic, does not mean there aren't solutions to overcome it. Toyota has repeatedly proven hybrids can be insanely reliable, as discussed in the video. Good engineering can overcome real problems. In the car world, it's often thought that "simple = better" but you can have something complex and reliable (Prius), and you can have something simple and unreliable (ahem, you know who they are). There's a lot of fascinating engineering that goes into making these things run reliably.
*2) Are the problems overblown?* It depends! As mentioned in the video, it's completely scenario dependent on whether you build up water/fuel dilution over time. Modern hybrids will have algorithms to address this as much as possible - with scheduled longer run times to help boil off water. For long distances, you can get temps high enough, consistently enough, to get rid of water/fuel. Even still, versus non-hybrids, you will see lower average temperatures, and short trips can exacerbate this issue (especially if the engine is turning on/off during these trips).
*3) How do older hybrids deal with these problems?* Many ways! One of the easiest solutions to ensuring you don't have too much oil/fuel dilution is a shorter oil drain interval. Changing the oil is a guaranteed way of getting those fluids out. The more frequently you do this, the less of a challenge it is. Modern engines are calling for longer and longer oil drain intervals - the video discusses a product which is designed to handle these longer intervals reliably.
*4) What about electric oil pumps; does that help with start/stop?* Sure, in many modern hybrids you have electric oil pumps - this can help provide oil flow prior to re-starting the engine. But not all hybrids have electric oil pumps; plenty (especially older hybrids) have mechanical pumps that only run when the engine is running. When you don't have oil flow, you're reliant on the properties of the oil - what film is left behind, as well as additives (like ZDDP, as discussed) to protect the engine in these scenarios.

[scott]

The amount of hybrids on the market going hundreds of thousands of miles on the original engine is proof automakers have enough measures in place to compensate for the issues raised here.

[Duckferd]

As a engineer who has worked in PCV systems, the first time we saw the condensation/moisture problem from repeated starts was not in PHEVs and hybrids... but actually normal ICE vehicles in dealership lots. During the winter, we noted that some dealers would move cars from one side of the lot to the other side as they clear the lot of snow. Over 30-40 of these 'cycles', they end up with substantial amounts of water in the crankcase, and we had to instruct dealers to leave the vehicles on to fully warm up to prevent this happening. Typically in small amounts this doesn't cause an issue, but as you imagine, problems started to crop up when that much water has accumulated in the engine. This experience was really useful when we got into PHEVs, because we developed two things: a counter to force the engine to turn on after a number of 'cold starts' to force a warmup cycle, and then an algorithm to modify (shorten) the oil change interval minder if the engine is still not given the opportunity to warmup (say if the customer has constant short drives).

As a tangentially related topic, moisture in oil is also how some oil catchcan manufacturers mislead, or at least inflate, claims about how well their products work. Today's PCV oil separation systems are basically like science experiments and incredibly efficient under most circumstances, but they do not filter out fuel and water vapour (those go back into the intake to be ingested). So when you see forum posts from oil catchcan manufacturers showing how much fluid they're capturing from new/modern street driven vehicles not subject to high G-loads, chances are that it's mostly water and fuel, and they never put that fluid into an oven to evaporate it and show you the true amount of oil they're actually capturing.

[toyotahontas]

I worked 22 years at a Toyota dealership, 1998-2020. I saw the advent of the hybrid -- and never saw a single engine fail.

[camtoufan]

Sum up: this video is a promotion piece for Mobil1.

[funlovingJohn]

Toyota Hybrid engines use 3 phase veriable speed water pumps and oil pumps controled by the engine computer. Even though the engine may not be running the water and oil pumps are running while driving. So thats two reasons why Toyota Hybrid taxi's with are still running strong.

[bizmar]

Recent research has shown that Nutella is a bad engine lubricant

[trudgemankPhD]

Sounds like a solved problem, but I like being educated about solved problems.

[tonycallahan]

I drive a 2016 Lexus IS300h. When the oil needs to be changed it's hard to believe because it is the same colour it was when it went into the car. I bought it about 10k miles since it's last service and took it for an oil change right away, oil was spotless. Now I have done about 5-6k miles since then and the oil is still ridiculously clean. I have never seen oil this clean in any car. This is because not only is the engine tight but when most of the oil wear typically takes place in a car (low speeds/city, idling), the engine is switched off and in EV mode.

[kevinbrown]

Love your videos but this one is just a little too connected to an oil company marketing its product. Hybrid engines are known to last a long time. My family owns three hybrids and never seen any signs of water in the oil in any of them. As you point out, oil sticks to surfaces keeping a level of protection in place and this is especially the case for frequent hybrid start/stops. Hybrids are also often managed to turn the engine prior starting to pre-lube it before turning on injectors and ignition systems. Finally, electric oil pumps are increasingly being used which can operate independently of engine rotation. So, Mobil is really highlighting a solution to an already solved problem to try to convince people to buy their oil.

[BadMuflon]

Taxi driver from Europe here.
We use Toyota hybrids a lot. They dont have any issues if maintaned corectly. Personally I drive a diesel Mercedes and I have problems all the time

[patrickvanderwyden]

I have 168, 000 miles on my Prius plug-in Hybrid. No problems at all. The "starting" is done with the electric motor, not with a starter. The Atkinson Cycle keeps the stresses on the pistons to a minimum.

[annunakian]

Not an engineer or a hybrid-owner, but drove a manual Civic thru deep flood waters twice. Almost stalled out twice. Had to downshift to make it thru. But each time, I made sure to keep driving for a few hours afterward to boil off any water. Also ran Sea Foam thru. I'd like to think that doing that helped. Car is still running like a champ other than a bad catalytic, 240k miles.

[NeoAutodroid]

People have been fearmongering around hybrids since the early 2000s but they have proven their reliability time and time again.

[RickJohnson]

For cold or idle starts, Toyota addresses the first concern by spinning up the engine to about 1000 RPM w/ the hybrid motor-generator closer to the engine (MG1) before introducing fuel and spark. This, along w/ anti-drainback valves in the filters, helps generate oil pressure more quickly.

They've also tried various methods of pre-warming or quickly warming the engine, from hot coolant stored in a thermos (2nd gen) to routing coolant through a radiator in the exhaust stream (3rd-gen), though arguably, both of those strategies were more for emissions than wear.

[aspecreviews]

Hybrids do not *cold start* their engines every time. My 2001 Prius waits until it's COMPLETELY warmed up to shut off initially. Ironically, that helps the engine stay off longer and under heavier throttle scenarios.

[Maleniabom]

Some of the most reliable vehicles Toyota makes are hybrids

[MTI]

Toyota hybrids mitigate some of the startup oiling issues by using the motor generator (MG1) to spin up the engine to the idle rpm before adding fuel and spark. While you still have the problem of cold oil, at least you don't have the rich fuel mixture dissolving the oil film from the cylinder walls.

[singular]

And yet toyota hybrids are THE MOST reliable vehicles in toyota's fleet of options.
I know people who have 15+ year old toyota hybrids that have 300k miles on them, no battery replacements, and basic oil changes every 10k miles.
Zero issues.

[liljawn]

I'm a technician and I just bought a new Ford hybrid 2 months ago. I waited extra time so I could get the hybrid package in my Maverick. Ford and Toyota embraced the technology 20 years ago and have a lot of R&D in the segment to work with. They're the only ones I really trust when it comes to a hybrid. If you want to choose a vehicle that is durable and meant to last, look at what taxi companies use. You can't touch an old Prius or Escape hybrid at an auction because the taxi companies will pay top dollar for them. Seeing either with 2 or 300k miles on them on original engines and batteries is not uncommon. The reason is simple.

Neither the ICE or the electric drive system is ever fully taxed. The engine comes on and runs at the point its under the least amount of stress, and the batteries are maintained at an optimal charge level almost constantly. This makes for a very durable, efficient drivetrain that will last a very long time.