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Sythetic oil and filter change intervals

I run only 5W30 synthetic oil in all my vehicles. I generally go no more than 4000 miles between changes and have traditionally done both oil and filter. While everything I read says change both at the same time how about just changing the filter at about 3000, then doing the oil every 6000. Everything I read tells me the synthetic doesn’t break down like regular motor oils so I would be getting first a clean filter and secondly a little shot of fresh synthetic oil. Any thoughts?

Does your Highlander require synthetic oil? You can’t extend the oil change interval that’s listed in your owners manual just because you use synthetic oil. Synthetic oil is good in the right application but for a normal engine it’s not really needed.

If you’re doing 4,000, you don’t need synthetic.

The owners manual recommends 5W30 at 7500 under “normal driving” conditions whatever that means. I ran regular oils for about 30K before the switch but with the same interval. What I do notice with the synthetic is increased gas mileage and almost no discoloration when changing the oil. It is never black . . . only slightly darker than when it was put in. Several of my friends wait for me to car shop so they can buy my cars. And I keep them over ten or twelve years.

The Toyota dealer has always recommended no more than 4000. When they increased their prices to the point of costing me more than switching to synthetic and doing it myself, I made the switch. The increased mileage is real by about 7 to 10%. I’ve checked it repeatedly. Would a synthetic blend be a better choice and go to 5K intervals? I want these cars to go over 200K.

If your vehicle is not used in severe service like towing, dusty or dirty roads and heavy hauling you could go 5K on oil/filter changes with no problem. Regular, synthetic or synthetic blend. It’s your choice.

Today’s oils don’t “break down”, mineral oil or synthetic…They BOTH slowly get contaminated with combustion products that blow past the rings. Motor oil gets contaminated with blow-by, that’s why you change it, period. How often do you change the oil in your rear-end?? NEVER is the correct answer for most people…Why? Because there is no blow-by to contaminate it. As engines age, blow-by increases and oil should be changed more frequently. Some people think synthetic oil can absorb UNLIMITED amounts of combustion blow-by because of what they read on the back labels of the containers of synthetic oil they buy. Their posts begin “From what I’ve read…”

The only thing you need to read is your owners manual. It will tell you when to change your oil…

I don’t care if you use synthetic oil or conventional oil, you should be able to go 5,000 miles between oil changes with no problems. You should change the filter and the oil at the same time.

wepedal, I think you have an OCD problem, and you are wasting both time and money. What you are doing is overkill IMHO.

Caddyman, what you recommend (never changing the oil in the rear differential), I think is a bad idea. Even differential oil usually has a change interval.

I certainly can’t debate you on the OCD . . . no question about it!! LOL! Just an old car nut from the 60’s and farm boy when we kept tractors running with bailing twine and friction tape. Everyone has pretty much validated what I thought . . . oil and filter at around 5K. But the increased fuel mileage is real or my math is very consistently bad. Thanks for all the input. You guys are a fun bunch.

It might, but it seldom happens…I think my Vics want it changed at 100K miles…NOTHING lasts forever, not even skunk oil…

Then there is another way. Buy the Fram filter that costs more and says to use it for 10,000 miles and just change the oil without removing the filter. Change the filter at 9,000 miles. Just because the oil is discolored doesn’t mean it’s not good oil.

You can use a WIX filter.

Humidity and dust does not discriminate on what type of oil is in the car.
It’s not always about the oil breaking down.

Thanks for the reply. I neglected to say that is exactly what I do. I use the Fram Extended Guard filters exclusively. I started sometime ago when I got into motor homes and the large block GM V-8’s. I had to have the oil pan replaced on a Honda (stripped threads in the drain plug). The mechanic came an asked what kind and what interval did I change oil. I thought he was going to tell me that had something to do with it. Instead he said it was the cleanest oil pan he had ever seen for a car with 160,000 miles. But all those changes and improper torquing took their toll on the drain plug. Now I use a torque wrench.