Synthetic oil in higher mileage vehicle?

[Scott's 62]

My Mazda just clocked 93 thousand miles and I am wondering if it would be wise to switch to synthetic oil. My wife puts quite a few miles on it per month so I would like to get a little more mileage between changes. Since I bought it a little over a year ago I have been putting Castrol GTX high mileage in it. What do you all think?

[Jarhead0754]

High mileage oil is a scam really. But really switching to a full synthetic now wouldn't really hurt anything. I've used synthetics all the time starting with castrrols syntec. But now I pay the little xtra and use royal purple for everything and I wondered why I waited so long. Mileage has been a lot better and when I took it to emmisions testing it scored off the charts which I was shocked at. All my cars now have royal purple synthetic oil, trans oil, power steering fluid, gear oil, I use their lube for any grease fittings. I use the radiator additive cool ice. And now use a can of the fuel additive every oil change which is 6k but they recommend as much as 15k. And I use their oil filters which I change every 3k as they recommend.

U pay a little more but my car runs so much smoother and efficiently. So I say if u do spend the little xtra and do royal purple and u will b impressed. I was and I was a sceptic.

[The Guz]

Re: Synthetic oil in higher mileage vehicle?

You will be fine switching to synthetic. Been running synthetic on my 99 Grand Prix since 30k miles. It now has close to 101K. When I had to replace the lower intake manifold gaskets, the engine was clean. My 02 Camaro came with Mobil 1 synthetic right out of the factory and I still use that.

I tried Royal Purple but I thought it was more hype. I would probably go Amsoil if I wanted to go with a premium brand. In all honesty, will be fine with any brand. I am currently running Quaker State synthetic (for about a year now). After this runs it's course I will be sending out to blackstone to get an oil analysis done on it to see how it performed.

[Jarhead0754]

Ur either an amsoil fan or a royal purple fan. But it's like either a Cubs fan or white sox fan, or Yankees or Red Sox. But the 2 def have a rivalry don't they guz?

[Scott's 62]

Re: Synthetic oil in higher mileage vehicle?

Thank you Guz and jarhead for your thoughts, I wasn't sure because I have never ran synthetic in any of my stuff before. My brother is running Amsoil in his ranger and he has had no problems so far.

[The Guz]

Re: Synthetic oil in higher mileage vehicle?

Ur either an amsoil fan or a royal purple fan. But it's like either a Cubs fan or white sox fan, or Yankees or Red Sox. But the 2 def have a rivalry don't they guz?

True. I'm not a hardcore fan of either. Mobil 1 has been good to me. Now I do like the Amsoil air filters much more than a K&N. So I am a fan of those.

[Jarhead0754]

Never tried amsoil air filters but I was happy with the k&n filters. But I would like to get an air raid set up as i hear good things bout them. But mobile 1 is pretty good oil and so is amsoil. Never tried them cuz I've had great success with the royal purple plus it's easier to get as no one carries amsoil by me but I'm def not against to trying them. I do think they are neck and neck in quality. People think I'm crazy enuf spending $10 quart as is

[DasBurninator]

Re: Synthetic oil in higher mileage vehicle?

Running full synthetic in both cars. The CC has had Castrol Synthetic its entire life, the GTI has for as long as I have owned it and its at 160k now.

Recently tried out Schaeffer's oil per a buddy's suggestion and noticed a couple MPG increase. Oil temps are a touch cooler as well. No hype on that one and about the same price as royal purp.

[The Guz]

Re: Synthetic oil in higher mileage vehicle?

Never tried amsoil air filters but I was happy with the k&n filters. But I would like to get an air raid set up as i hear good things bout them. But mobile 1 is pretty good oil and so is amsoil. Never tried them cuz I've had great success with the royal purple plus it's easier to get as no one carries amsoil by me but I'm def not against to trying them. I do think they are neck and neck in quality. People think I'm crazy enuf spending $10 quart as is

The reason I like the filters versus K&N is the only cleaning involved with the Amsoil is a quick blow with the air compressor. No need for a cleaning and re-oiling like a K&N. I don't have enough time to play around with a filter like that. The Amsoil filters flow just as good if not better than a K&N.

[Top Gear]

Re: Synthetic oil in higher mileage vehicle?

My two cents: This is a "snake oil" issue (in this day and age, anyway). I've had engines with and without synthetic, and it's generally not wise to switch after the engine has been well run-in. It might work, and it might not. Castrol GTX is one of the very best, and the HM is a synthetic blend, anyway, so there's absolutely no reason to switch, as there's no actual upgrade here, and you've already switched oils. Pure synthetic is great for a racing engine and best when used from the start during break-in, not after you've already basically worn the thing out. If you really think GTX is affecting your mileage (and I very much doubt it), you could look to the weight, not the brand or type. For example, if you're running 20/50 where you are in Northern California, drop down to a slipperier weight like 10/40 or 5/30. You also should run a "Top Tier" fuel, which will have a dramatic affect on mileage and performance.

[Don]

Re: Synthetic oil in higher mileage vehicle?

@ Top Gear

While I agree with you in the point that modern oils have far surpassed their humble beginnings (engines were originally lubricated with mineral oil) I can't agree that synthetics are snake oil. I used to work at a quick lube shop and like non detail oriented people love the swirl o matic car washes, non car people love the quick oil change shops.

I have seen while working the lower bay, cars that have come in with 9,000 miles on regular oil and you could tell the instant you cracked the drain plug because you could smell charcoal and the oil coming out was pure black. That oil was toast and probably causing as much or more damage than it prevented.

When a car that had been running synthetics came in, the smell seemed 'clean' to me, like it wasn't time to change it yet, and it was only a darker brown color, but the upper bay guy would tell me the car had over 10,000 miles some other ridiculous amount of miles on it. I talked to a few of those owners and they said that it (synthetic) cost more in the beginning, but since they were able to extend the oil change intervals it actually costs less. Plus they would notice a slight MPG improvement. So because of that, I switched from Penzoil 10/30 to Amsoil 0W30 and when I 'LOST' my Amsoil dealer, I went to Mobil 1 Extended Performance 0W20 and I haven't had a regret since.

Possibly the only draw back to synthetics is their cleaning ability. If your car already has leaking gaskets, the synthetic oil will clean out the sludge in those gaps and make the leak worse

[Top Gear]

Re: Synthetic oil in higher mileage vehicle?

I'm sorry, I exaggerated that aspect, Don, and I agree with you. I did not mean synthetics are snake oil, but that switching to a synthetic for a non-performance, non-new, possibly warrantied, commuter car is snake oil. It is as likely such an engine will start to burn oil due to the extra lubricity of the synthetic slipping past valve guides and rings. I just think it's an unnecessary risk for an unnoticeable change.

Of course, the best advice is to NEVER drive on regular oil past 3-4k miles or so (my factory intervals are 3,750 mi.), even though some oils are rated to last 10k. Even with a full synthetic in a fresh engine, running some 10k on a change just because the synthetic oil can take it doesn't mean the engine can take it that long without fresh oil. Most people just need to follow the 3k rule or follow their manufacturer's recommendations, instead of presuming a synthetic will solve their problems, because it very likely won't. Using synthetic oil just to avoid changing oil at recommended intervals or in the hopes of getting better mileage is specious reasoning at best. That's what I meant by snake oil.

Oh, and quick change places are great. I've used them in previous cars (this one goes to the dealer on a service plan). I went in purely for the oil and filter change and recycling, always paid extra for Castrol GTX, never going past 3k miles. I had one car with 225k when I sold it, and the oil never went black, never had a drop of synthetic, either

So, I think we can get so focused on saving the smallest amount of money we completely lose sight of the bigger picture

[innovated]

It looks that everyone has good experience with what oil u should use.. but let me ask you this what kind of mazda is it? Because theirs a mazda that you should NOT use synthetic oil on it?

[Scott's 62]

Re: Synthetic oil in higher mileage vehicle?

It looks that everyone has good experience with what oil u should use.. but let me ask you this what kind of mazda is it? Because theirs a mazda that you should NOT use synthetic oil on it?

It's a CX-9 with the Ford Duratec v6. They say to change the oil at 5 thousand miles so I figured it wouldn't hurt to use synthetic oil For a little more protection from the longer intervals.

[The Guz]

Re: Synthetic oil in higher mileage vehicle?

Amsoil and Mobil 1 have their own line of synthetic oil that have about a 10k mile interval change. With synthetics I typically change every 6k miles. My daily commute is short and I maybe drive roughly 3k miles a year. I change the oil twice a year. On my Camaro that I drive only on the weekends or every now and then, I change that out once a year.