Skip to main content
lou's garage

I have a 2005 Toyota Sienna XLE 3.3-litre, with 267,000 kilometres. I used conventional oil at my last oil change with 5w30 GTX at 245,118 kilometres. I am due for another oil change and I was recommended an engine flush and switch to synthetic oil. Should I do both? – Roman

I’m sure you’re going to take some heat in the comments section when this is published online, Roman, as 21,882 kilometres on a single oil change is a large misjudgment in maintenance.

In your defence though, I also know it happens more often than most drivers will admit. Given that your vehicle has made it to 267,000 kilometres, I am going to assume that this isn’t a regular occurrence for you.

Your vehicle’s 3MZ-FE motor as found in many Toyota products of this generation was a robust power plant with few problems. It is easily capable of many more kilometres than you currently have and will probably be okay if this is just a one-off fail in maintenance.

An engine flush is tricky at this point as there are many who suggest that flushes on vehicles with high kilometres may actually dislodge sludge, which in turn causes an oil gallery to be blocked, which then may create a problem. If you are really concerned, you can have the front valve cover temporarily removed and the engine checked for sludge buildup. Otherwise, I would stick with conventional oil, pass on the flush and perform the next few oil changes a bit early.

Is it a good idea or necessary to change the automatic transmission oil, especially in a high-mileage vehicle? I drive a 2005 Toyota Tundra V-8 with more than 300,000 kilometres that I service regularly, but never the transmission. – Dave

After 300,000 kilometres of service, this transmission owes you nothing. According to the maintenance guidelines at, your Tundra should have received a transmission oil service every 96,000 kilometres.

I’m speculating, but I believe you have asked your question here today because you have read all kinds of horror stories online – stories such as transmission failure immediately after a recent service on a high-kilometre transmission.

Simply as I can put it, when automatic transmission fluid has not been changed in a timely fashion, remnants of the wearing clutches turns that fluid into sticky, sludge like goo that basically holds things together.

Changing the fluid will bring about an immediate viscosity difference and may lead to issues that are perceived as not having been there before.

I regularly hear of shops recommending against fluid change at this mileage. They do this because they do not want to have to deal with the aftermath. You can certainly keep driving it as it is and hope for the best, or you can take it in and have it serviced and flushed.

There is no correct answer here; either way you are taking a gamble. If it fails immediately after a service, it’s not the fault of the product or service, but poor maintenance.

Lou Trottier is owner-operator of All About Imports in Mississauga. Have a question about maintenance and repair? E-mail, placing “Lou’s Garage” in the subject line.

Shopping for a new car? Check out the new Globe Drive Build and Price Tool to see the latest discounts, rebates and rates on new cars, trucks and SUVs. Click here to get your price.

Stay on top of all our Drive stories. We have a Drive newsletter covering car reviews, innovative new cars and the ups and downs of everyday driving. Sign up for the weekly Drive newsletter, delivered to your inbox for free. Follow us on Instagram, @globedrive.