i just made the switch from dino to Castrol Syntec and my motor is 10 times Quieter and smoother also I have picked up another 4mpg <img src="/forums/images/graemlins/cheers.gif" alt="" /> <img src="/forums/images/graemlins/cheers.gif" alt="" /> <img src="/forums/images/graemlins/cheers.gif" alt="" /> anyone else notice this? also for you guys runing syn. in higher mileage engines that burn a little what does it leave behind for deposits the reason I ask 2 of my other toys are Mazda RX-7's and the rotarys in them have an injector pump that meters oil into the intake to lubricate the rotors so synthetic has always been black magic with them. <img src="/forums/images/graemlins/evil.gif" alt="" />

I bought my 94 with 114K from the original owner who always ran penzoil or some other crap on sale along with a fram filter. I bought it in September 03. I switched her over to 10W-40 AmsOil and a Toyota filter. Let me tell you how black it got and how fast! I just changed it yesterday (7 months 10K later) again... same set up... toyota filter 10W-40 Amsoil and NOW she's running differently....better:) Wouldn't know how it runs on regular oil..never ran it in my 4runner. I do notice 1 thing now since my change yesterday.. about 6K afer the initial change i started losing oil pressure at idle. Well, that's due to so much crap in the filter!! I now have my oil pressure back at idle! That's how much crap the AmsOil was flushing out.. it actually was clogging up the filter. I also did notice the valve noise got quieter after a few months of running it. I LOVE AMSOIL! My engine had a lot of deposits in it. We'll see how fast this 2nd change gets dirty. I deffinately reccomend a Synthetic Oil.

Just to let you know.. Castrol Syn isn't actually synthetic oil. It's regular Oil that has been "highly filtered". Mobil 1 sued castrol a few years back. Castrol won the law suit b/c the laws state that synthetic just means X amount of "man interaction". So if they filtered it enough.. it's been man handled enough to be called synthetic. I'd switch to Mobil 1, AmsOil, Royal purple or redline. Just my 2 cents.

I switched from Castrol GTX to Mobil 1 in my wife's car, and I also noticed an increase in fuel economy. The synthetic is, of course, more expensive but I recoup my cost by getting better fuel mileage, and I can now go 5000 miles between changes instead of 3000.

I won't use synthetic in my 4Runner because it's had the regular stuff for just under 250,000 miles, and I hesitate to make any waves. It also likes to burn a little oil, and it would burn much quicker with synthetic.

Keep that in mind, by the way - if your vehicle burns or leaks oil at all, it will go through synthetic a lot quicker than regular oil.

I agree with J94 in that Castrol is not what I call a "true" synthetic. In most areas of the country, Mobil 1 is the only true synthetic oil available over-the-counter. What I call a true synthetic is oil made from Group IV base oils (polyaphaolephin...PAO) and Group V base oils (esters and others). Other true synthetics are Royal Purple, Redline, Amsoil (except their XL-7500 series).

Castrol Syntec (except maybe the German imported stuff sometimes for sale in Canada) is made from very highly refined petroleum with the legal right to call itself "Fully synthetic"...this is Group III base oil. Pennzoil & Quaker St. syn, Shell syn, Chevron syn, Petro-Canada syn, and all the rest are also GR-III.

Syntec is good oil, not quite as good as full synthetics such as Mobil 1, so everyone has to decide if the extra cost is worth it based on their driving habits. If your engine is operated occasionally under severe conditions I'd highly recommend using a full synthetic over Gp IIIs, blends or Dino.

I don't think synthetic oil will do much relative to "flushing" your engine. In most cases when changing from Dino to synthetic you probably don't need to flush the engine but if you "feel the need" or know your engine is gunked up, then flush your engine using a "specialty" chemical that's manufactured for that purpose. There's several on the market that will do a good job but the one I'd recommend is CFL OIL sold by Lubriplate. Put a quart or quart and a half in, drive 300 miles and you'll "puke" your engine almost spotless. <img src="/forums/images/graemlins/cheers.gif" alt="" />

5,000 mile oil changes!??! I change my Amsoil & Toyota filter every 10,000 miles! Regular oil can go 5K on today's engines.

Related, possibly? Maybe even a little contradictory?

Maybe you should at least change your filter every 3,500-5,000 miles... Low oil pressure due to clogging can't be good for your 3.slo! <img src="/forums/images/graemlins/rolleyes.gif" alt="" />

I use nothing but Valvoline 10/40 and a fram o/f! It stays clean pretty long and it doesn't burn! It is a little louder though! I get 21 mpg! I use to use Castrol but my 3.0l didn't like it, I use to burn about a qt and a half between changes! I change my oil every 3000 miles or less, and you all should too!

Purolator and Pennzoil here, seen too much bad about Fram filters getting clogged and being worthless. I tore my engine down at 200k and could still see the original crosshatches, just did a little honing and slapped some new rings in and it's been great for 60k more so far. I love the synthetic in my tranny and tcase, but I'll stick with dino for everythign else<img src="/forums/images/graemlins/pfft.gif" alt="" />

I've been told that, but the miles around here tend to be kind of rough. I live in the mountains, so there's a lot of hill driving, and my wife (the main driver of the car with synthetic) is a stay-at-home mom, so it doesn't see regular commuting duty. It gets a lot of short runs, long drives and everything in-between. After 5000 miles (takes about 4 or 5 months) the oil is pretty dirty.

The oil in my 4Runner gets changed every 2000 miles. I drive it daily to and from work, but it's only 4 miles round-trip, and the rest of the miles are off-road. It takes me about 4-5 months to put 2000 miles on the 4Runner.

What I was taught, was that synthetic oil molecules will not break down at high temp. like dino (dino generally doesnt break down in normal operating conditions). As far as cleaning and lasting longer, this has to do with additives, detergents and anti-acid additives. so, does mobil 1 syn have way more additives than any dino? I dont doubt it can lubricate better, but if all those additives get used up then the oil will be damaging to the engine no matter how superior the lubricating oil is. remember that lube oil can be recycled, the oil doesnt wear out, the additives get used up, carbon and acids. Anyone care to elaborate , disagree etc?