My 4runner V6 has always run on conventional oil. It has 200k miles on it. Synthetics have come way down in price. I'm wondering if i should make the switch to high mileage synthetic.

Hardly any reason not to imo

Do it

MANY! opinions on this one. I'd say it depends. If you change oil every 3,000 miles and you're not burning oil, then it's probably not worth changing to a synthetic. I use a full synthetic and change my oil & filter @ 5,000 miles, but an oil analysis suggested I'm wasting money and could likely go at least 7,500 miles between changes. I use a high-mileage formula, even with only 85,000 mi on the car. I do this because it's a 2008 (i.e., old), I plan to keep it forever, and I'm hoping the oil really will condition the seals.

If you're having to top up between changes, a synthetic might help since synthetics are less volatile than mineral oils (i.e., depends on why it's using oil). There are many important factors, so I don't think there's a simple answer, other than if it makes you feel good, do it.

Oil analyses are informative and inexpensive. A WIX oil analysis kit (also good for transmission fluid) is currently $9.50 from RockAuto (you also pay postage on the sample; WIX 24077). An analysis is really the only way to make an informed decision and I think an incredible bargain at that price.

Synthetics are undeniably better oils it terms of shear, longevity, etc., but they might not be either necessary or an improvement for your specific situation.

See BobisTheOilGuy.com for another thousand or so opinions on this one.

thx for that info. one of my hesitations is i believe i've heard that once one goes synthetic, you cannot (should not) go back to conventional in the future. true?

Absolutely not true.

Synthetic is the way to go. My last car went for 472K miles, I would have hit 500 but some douchebag rear ended me. My goal is for my 4Runner to hit at least 300K.

I have a slightly different opinion, when i switched to synthetics from dino oil, the synthetic cleaned the engine, and swept out lots of dirt. so if there is a chance our engine isnt clean, on switching to synthetics for the first time, you may want to perform an oil change early enough say 1k miles/3weeks

Get on the mobil1 rebate. You can even stack with other discounts.

Ex: 6 quarts at costco for $38 - $10 (costco sale) - $12 (mobil1 rebate) = $16.

Stock up when there are sales, then you hardly have a reason not to run top notch, full synthetic motor oil.

I did so much reading on this subject that I literally got tired of the subject.

At the end of the day I learned that yes, there is absolutely a difference in the quality and technology of the oil, but I still continue to use conventional and change it regularly before it starts to break down and offer less protection. Personally I am just good with that program.

Our 5th Gen uses synthetic from the dealer, but the 4th was born with and has never seen anything other than conventional over the past 200k+ miles.

I think my reluctance to change came more from the fear of having issues (if any) after switching to syn. Seals, cleaning, moving around debris… I don’t know. I figure I just leave good enough alone. Its got 200k on it, and it just keeps working. No need to complicate it and start adding new variables. My concerns could be 100% unfounded but that’s what I am sticking to.

I take my V8 4th gen to a smaller independent shop for all my services. The gentleman who runs the shop used to head up a Toyota service department. He's adamant that Toyota's run clean and burn little to no oil so conventional is plenty fine, and it can even go 5,000 miles between changes.

I've been following his word without a single hiccup. Nearing 150k miles, conventional changed @ 5,000 intervals, works for me.

I'm been running synthetic since I got the runner (at ~70K) and have been doing my own oil changes (now almost 130K).

I don't have any issues with it and change at about 5000 miles or every 6 months. So for me spending the 50 bucks a year on oil isn't going to brake the bank. And if it extends the life of the motor and improves performance, that's cool to.

If Syn makes sense then do it...

Now that I don’t daily drive this thing… I change once a year.

Last oil change was 02/2017 to 10/2018 and all I did was 703 miles and I went over a year.

Even with synthetic they say to change based on time… I would end up dumping out very expensive oil with low mileage on it. Another reason I just stick to conventional.

i might get flamed for this question, but is there really much difference between different brands (including store brands) of synthetic oil (or conventional for that matter)?

Quite a bit. PQIA conducts independent testing of motor oils and reports their findings here:

http://pqiamerica.com/PCMO_Sample_Su...2_15_2016.html

Don't let the URL page name throw you off, it includes all 2018 test data. You'll see quite a few store brands that failed to meet API specifications, and you'll see wide variation in characteristics that reflect quality such as Total Base Number and additive concentrations.