Synthetic oil

I way I read your OP, the dealer may be correct in saying that the “2008 ES 350 isn’t built for synthetic oil, like the later models are”… but that doesn’t say that synthetics can’t be used or an oil that is ASE spec.

I’d be certain that if you specified a synthetic to your dealer, that they would be happy to accomodate you plus the appropriate profit margin.

BTW, did the dealer say that the engine isn’t made for a better qualty oil filter?

@NUPE I way I read your OP, the dealer may be correct in saying that the "2008 ES 350 isn't built for synthetic oil, like the later models are"... but that doesn't say that synthetics can't be used or an oil that is ASE spec.

What does it mean when you say it’s NOT build for synthetic oil. That statement makes no sense.

+1 to CSA’s post.
The dealership is giving you good advice.

Change the oil every 5,000 miles with synthetic and you might (I emphasize MIGHT) prolong the life of your engine.

Change your oil every 15,000 miles and you will prolong the life of your oil…probably at the cost of reduced life to your engine.

Is your goal to prolong the life of your engine or of your oil? You choose.

Synthetic oils contain fewer impurities than dino oils, and they have mor econsistant molecule size. That enables them to with stand heat better (fewer impurities) and lubricate better in extreme cold. But all oils become contaminated with the same amount of impurities and diluted by the same amount of blowby at the same rate, and that’s a major component of oil deterioration. The manuals for turbucharged engines mandate synthetic oil because turbos are heated by the exhaust and high operating speeds (200,000 rpm) and synth is less prone to damage by the heat.

In summary, if your goal is longevity of your engine, stick with the 5,000 miles oil changes. If you feel more confident doing so, also use synthetic oil. But do not extend the times between oil changes based on the use of synthetic oil.

“The state police in our state use synthetic oil and 10k oil changes”

Police cars have very different driving conditions than the average passenger car.

And state police CARS in our state are put up for sale at 150k miles. I’d like to see those engines at 300k miles.

“And state police in our state are put up for sale at 150k miles”

You are going to edit that aren’t you?

I don’t own a Lexus either, but my daughter does own a Corolla and its owners manual says to change the oil at 5000 miles for conventional oil and 7500 for synthetic. So NUPE, look in your owners manual to see if it says the same thing. If it does, then the dealer is obviously wrong about not being made for synthetic oil and you can safely extend your oil change interval to 7500 miles if you use it.

Now it comes down to economics and preference. Calculate the cost per mile of an oil change using synthetic oil for 7500 miles vs the cost of an oil change using conventional oil for 5000 miles. I suspect that if you are not doing your own oil changes, the the cost will be about the same. So now it is simply a matter of preference.

BTW, all this talk of gums and deposits building up in the oil is not entirely accurate. Its not wrong exactly, but the reason you can go longer with synthetics is that they do not form the gums, varnishes, sludges and other deposits as fast as conventional oil. You see, oil itself is the primary source of these contaminates, these are formed as oil breaks down and synthetic oil does not break down as fast. The engine is well sealed against other contaminates and with computer controlled fuel injection and ignition, deposits from unburned gas is almost non existent as long as your engine is running properly.

Synthetic for autos have been around for 30+ years and longer for airplane engines.
Can anyone find a auto that has failed or needed repair because of the use of synthetic oil. In the 70’s I heard that synthetics was an indirect cause of engine repair…

My mom’s 60yo oil furnance runs great on diesel although its made for heating oil.

Longprime, I’m unaware of and would not believe that any engine would be damaged by synthetic oil. That’s clearly myth.

I can, however, testify to numerous engines that succesfully ran on dino oil for hundreds of thousands of miles until other issues finally put the vehicles out to pasture. Including my beloved Toyota Pickup.

In My Opinion, Taxi Cabs, Police Cars, And Other Cars That Are Started And Brought Up To Operating Temperature Where They Run For Hours At A Time, Can Go Longer Between Oil Changes, Even Considering The High Speed Bursts That Are Part Of Emergency Service.

I am going by gut, no facts or research, but frequent cold start, short trip driving seems like it puts more wear on engines and stress on oil.

When I worked at a small airport, the Chief Mechanic, a well respected A&E mechanic, would come unglued if we ever fired up a cold aircraft to taxi a short distance across the airport. We were to use tow bars. To this day, I use the same strategy with my family car fleet - don’t fire up a cold car unless one intends to drive it for a while.

I’m not so sure that 10,000 mile oil change intervals for State Police Cruisers hurts anything. For the average car owner, not so much.

Besides, a goodly number of average car owners would run out of oil before reaching 10,000 miles, since they don’t know what an Owner’s Manual is or a hood release is located. Perhaps the old 3,000 mile interval (profit enhancer) that is often recommended has saved many engines from that end.


Police cars…and aircraft…and flightline workers…have entirely different needs than the average driver. And all receive entirely different maintenance than the average driver’s car.

I’d just stick with mineral oil and change it at factory recommended intervals. That’s always worked for me on my GM and Honda cars.

I remember (70 and 80’s) some say that if you use synthetic, to do a 50% mix and then dump after a few thousand miles, and then do a full 100% synthetic replacement and again change early. Supposedly the synthetic has properties/solvents/additives that loosens the “gunk” from the mineral oils.

NUPE, this sort of discussion on oil usage and changes is old hat here. Same differences of opinion, mostly guesses, presented as science.

I really don’t give a hoot when people change their oil. If someone wants to change his oil every day, that’s his business. Ditto for those who want to change it every 5,000 miles. However, to present a personal choice as somehow scientific or superior, that is a problem.

So, several years ago, I drove my Mobil-1 EP 8800 miles and then had the oil tested. What do they call that lab? Blackstone? I forget.

Mostly highway driving, long distance,though that 8800 miles did include some rural Mexico driving at low speeds non-stop, not in the snow zone, high mileage 2002 Toyota Sienna. (thus not limited by warranty requirements.) Different car, different driving pattern, will make a big difference, of course.

In this case, testing showed all parameters good, and additives good for several thousand miles more. No filter change, yet the oil was clean which indicates no filter change was needed.

No guessing. Pure science. For my driving conditions.

If you want to know what is right for your car, or driving conditions, pull a sample at your normal oil change and have it tested. Be sure to do it for both summer and winter driving if you are in the snow zone. Then, you will know, no guessing,

On the other hand, if that is too much bother, jump on the every 5,000 mile change bus. Just do not come on here and present your decision as the only real choice, and do not mock those who don’t agree with you.

Note my 2002 Sienna now has over 193,000 miles on it, still not using oil.

Gee Irlandes, in the very post that mocked us for disagreeing with you, you told us not to mock those of us who disagree with us. Interesting approach.

Do I have scientific evidence to back up 5,000 mile changes (for those driving long enough each day to warm up their engines)? Not exactly, but the reports from the GM cars with OLMs (which count number of starts, length of trip, and other things related to oil life) typically call for changes at around 7,500 miles. So that satisfies my scientific side that 5,000 is typically just fine.

Irlandes, one more thing; I adamantly support your right to drive your cars as long as you’d like on the same oil, even if overwhelming evidence exists that to do so results in gunked up engines.

Realize, however, that your “pure science:” sample size is 1.

@Mike Synthetic for autos have been around for 30+ years and longer for airplane engines. Can anyone find a auto that has failed or needed repair because of the use of synthetic oil. In the 70's I heard that synthetics was an indirect cause of engine repair...

@Longprime - Why you arguing with me. I’m an advocate of Synthetic oil.

And as for your question…Can you find an auto that has failed or needed repair because of the PROPER use of dyno oil?? Up to 150k miles I say NO. But I keep my vehicles past the 300k mile mark…and I tow a lot during the summer…and the cold winters I use synthetic.

Sorry. Not my intention.
But did the benefits of Synthetics really loosen dino sludge and coat the engine?
IMO,Modern motor oils are pretty much interchangeable.

“oil was clean which indicates no filter change was needed”

“Pure science” suggests that filters get more efficient as they “load up” with use
(and rising pressure drop is the main reason for replacement).
So the oil “cleanness” wouldn’t determine if it’s time to change the filter.
It only shows that the filter is still doing its job.