Synthetic oil

My wife says the local Lexus dealership repair shop said her 2008 ES 350 isn’t built for synthetic oil, like the later models are. He said even with synthetic oil she would need to change every 5000 miles, so she might as well buy regular oil. I thought we could change every 15,000 miles and use synthetic. Is the dealer correct?

Choose Synthetic ( Or Not ) Because It Is Superior Oil, Not To Extend Change Intervals.
I Run Mobil-1 Extended Performance In My Cars And Change It Every 5,000 Miles.

It Flows Better In Cold Weather Starting And Protects Better At High Temperature, With Less Chance Of Sludging.

Since I change my own oil, the Mobil-1 costs less than an additional 10 bucks per change.


The dealer is WRONG…but so are you.

There’s no such thing as a vehicle that’s NOT EQUIPPED to handle synthetic oil. That is one of the dumbest lines I ever heard.

But you are also wrong into thinking that you can extend your oil change interval to 15k miles by using full synthetic. You still need to change the oil at the recommended oil change interval of 5k miles or you run the risk of voiding the warranty.

My wife owns a 07 Lexus ES 350. Exact same engine as yours. I use Mobil-1 and I still change the oil every 5k miles. The Mobil-1 is nice to have for these winters when temps drop to -10. We also keep our vehicles past 300k miles. So the added protection of Mobil-1…it’s worth it for me.

Like CSA said, dealer’s wrong, you can use, it, but right that using it does not change your maintenance interval, unless you choose to use the Mobil1 extended change oil (not just regular Mobil 1) and live by their guarantee terms.

I Don’t Know A Lexus From A Lamp Shade (Not Sold Around Here), But Isn’t It A Deluxe Toyota ? Pardon Me, But Why Do You Want to Scrimp On Changes - Convenience, Cost, Etcetera ?

I run many cars at our house. I change my own oil to make it convenient not to have to schedule changes with somebody else and to find the time. I do it on my schedule. Also, I use the oil and filters I choose and make sure it’s done correctly. The money savings is a plus. I can always find someplace to put the money saved.

Is DIY an option ?


Just use regular oil and change at 5000 miles. The only synthetic I use is for the 0-20 grade because it only comes in synthetic. I still change at 5000 miles. You can’t and shouldn’t extend oil changes by using synthetic even though lots of people do. That’s why you should buy a used car at your own peril.

An extended change interval oil must have enough additives to prevent acids forming in the oil. Just being synthetic does not do this. Mobil1 Extended Performance does have about twice the additives, and you can read about this oil here:

You will also need a filter that lasts up to the mileage you choose to run between changes. If you choose to use an extended change interval synthetic oil, make sure you know enough about it to use it successfully. Read all the information available from the manufacturer. You are out of warranty on your car so that is not an issue.

One more thing: make sure you don’t go past the time limit Lexus imposes for oil changes, no matter what the mileage is. If you drive less than 10,000 miles per year, switching to an exptended performance oil makes little sense.

Good responses all; If I owned a Lexus and wanted it to last a long time, I would use synthetic in grade 0W30. It flows at -50F and provides excellent film strength at high operating speeds and temperatures.

I would observe the manufacturer’s recommended interval, which is 5000 miles for a Toyota and would be the same for a Lexus.

And the dealer is full of hot air; synthetic is fine for your Lexus. The dealer just may not stock it.

As an aside, I’m amazed that a 2008 vehicle has a factory-recommended change interval of only 5,000 miles. My mother’s 2004 BMW is twice that, as is my own Suzuki. I’m all for good maintenance but I like to use the stuff fully and not waste it.

Your BMW holds a relatively large amount of oil in its sump, so it “wears out” more slowly.

“As an aside, I’m amazed that a 2008 vehicle has a factory-recommended change interval of only 5,000 miles”

My 09 Pontiac has a change interval of 3000. Its only recently that they started going nuts on the extended maintenance. Time will tell but be very careful buying a used car. Few people change more often than they have to.

" Few people change more often than they have to. "
Some People Don’t Even Check The Oil When They’re Supposed To.

Whatever You Do, Check The Oil Level Regularly And Frequently.

@Bing - that’s for severe service, right? And I thought GM had OLMs in their cars - is this a Vibe?

The state police in our state use synthetic oil and 10k oil changes. They have relied enough on studies along with having enough experience to indicate that it is economically more practical to do it this way. That does not mean that their cars get the most life, but starting from cold with you foot on the floor mashing the accelerator as a routine happening is better served by a synthetic oil and the state isn’t going through the expense of changing the oil more often. Right now, I’m in the 5k camp and if I plan hard use, I would use synthetic, especially if it were called for. But, in 5 k miles of normal driving, our biggest concern is not to over change your oil to no advantage in having the car rust out 100000 miles before the motor dies… Standard oil is fine for most of us.

Maybe all cars should come with dual-bypass filtration systems and super-long oil change intervals (100k?). Ought to be good for the environment. Still gotta change those filters, though.

Not sure about the OP’s car specifically, but synthetic can be good choice for many cars. Synthetic leads to a cleaner engine (on the inside) and can improve mpg a little. The downside (besides the steeper price) is that synthetic leads to a cleaner engine. By this I mean : the dirt and gummy deposits have to go somewhere. And they go into the oil. So it’s quite important the oil change interval not be extended beyond what the car’s manufacturer recommends for routine oil changes. What does 4 quarts of synthetic oil cost? $30? I think $30 every 3,000 miles isn’t that big of an expense, when it is protecting a $7,000 engine.

There’s one other downside to synthetics though: Oil leaks. Some engines which have operatedfor years actually have leaks, but they don’t actually drip any oil onto the ground because the gummy deposits from using regular oil have blocked the leak. But when sythetic oil is introduced into the system, over time it cleans these deposits out, and then the owner of the car may discover the engine is dripping oil on the pavement. To me, if I switched to synthetic oil on my 20 year old car, and what I ended up with was an oil leak and grease spotted driveway, well, I wouldn’t be amused.

" What does 4 quarts of synthetic oil cost? $30? "

That Would Be $7.50/Quart.

I buy Mobil-1 Extended Performance @ $27 For 5 Quarts Or $5.40/Quart.
The Regular Mobil-1 Is Even Cheaper.

I don’t think I buy the theory about the oil getting dirtier. Mine looks mighty good after 5,000 miles. The engine stays very clean, too.

Also, I believe the thing about synthetic and leaky seals is an old wive’s tale.


Synthetic oil costs nearly $100 for 5 liters where I live, about a full days work on minimum wage after tax. I know oil is cheap in N-A but it makes no sense to waste it in the bigger picture.
Despite the price I consider using a full synthetic (group III) worthwhile, and I always get my money back on resale value.

@KiwiME My brother’s Toyota Highlander has the same engine as OP. It calls for regular oil and 5K oil change intervals. The oil change reminder comes on every 5K, like clockwork.

Unless I’m mistaken, your 2004 BMW calls for fully synthetic mobil 1 oil, perhaps 0W40. Those european cars that call for the fully synthetic oil have been on extended oil change intervals for some time now. My mom’s 1999 C280 uses 0W40 fully synthetic and calls for 10K service intervals.
And yes, the crankcase holds slightly over 8 quarts.

@texases Its a G6 with the 3.5 V6. Could be severe since I usually use that anyway and it does have the OLM. Its usually about 50% at 3000 miles.

@dagosa I don’t know what the Minnesota Patrol does since its up to the individual patrolman but the normal pool vehicles are all changed at 5000 miles. Synthetic is not used unless the weight calls for it. Patrol cars could go longer since they are running all the time and on the highway. Like many areas though, professional fleet management went away with the republicans.