Oil preference - synthetic or dino?

[islandmon]

I'd like to hear some of the advantages of synthetic over dino oils for autocrossing.
For pushrod V-8's I used to use straight HD 30W dino (Valvoline, Castrol) sometimes with an additive like Lucas Stabilizer then sometime in the late 90's switched to Mobil 1. I ran Mobil 1 in both the Sti and the S2K. I have straight HD 30 W in the Mustang with Lucas Stabilizer (on Rob's recommendation) as a break-in oil.

I'm thinking of going to a synthetic race oil like Royal Purple or Redline and would like to hear from some of you. Are the synthetics worth the extra money (2 or 3 times as much)? How often are you doing oil changes with a dedicated autox car with dino? With synthetic?

Thanks for your input.

[Loren]

The short version:
Synthetic oil molecules are smaller and more uniform, so will ALWAYS work better when tight tolerances are involved.
Synthetic oil tolerates high heat much better than conventional oil and for much longer periods.
Modern conventional oil is good for a 5-7k change interval in a normally driven street car.
Modern synthetic oil is good for a 10-15k change interval in a normally driven street car.

The question is: are you really going to stress the oil that much in a car that only does autocross? For a track car that's gonna get REALLY hot for long periods of time, synthetic oil is a no-brainer for the extra protection. But, for an autocross car that's only going to be run for about a minute at a time?

The other question, if you're not really overstressing the oil... are you going to change the oil frequently, anyway? If you're NOT going to gain the benefits of an extended change interval, and you DON'T need the extra high-heat protection, then it's probably not worth the money to use synthetic oil.

The phrase "I change the oil every 2500-3000 miles with synthetic oil" is one that makes no sense to me... but you hear it all the time.

[twistedwankel]

In a high compression "fresh" autocross 306 I used 5 quarts of 20-50 Valvoline dino racing with excellent results for many seasons. I put an hour meter on the car so I'd know exactly how many hours between changes. Changed oil once per season - never had to add any between changes. Always came out clean with no metal in the filter.

I believe most wear occurs on startup so I like a lower vicosity for cold startups and a higher number for temps depending on the compression.

A "blend" can be achieved by substituting one quart synthetic in 5 (20%) which is all they do at the factory. No magic. Probably cost the same as just buying the blend?

I've also know racers who mixed two different vicosities 50/50 to achieve what they wanted with success over time.

You do whatever works for you. I could show you the world's longest diatribe on use of syn vs dino in the RX8 Renesis...Moan. Even Mazda uses full Synthetic for racing when there is no cat to foul. (Direct injection.) I use the recommended Dino only to save the Cat designed to burn it. Normally wait for sales at Mazda and they have been using 5-20 Chevron for years in all of them. Oil does 1/3 of the cooling in a rotary and doesn't have alot of moving parts.

For my other 2 old Ford V8's (86 and 93) that I normally let the local shops change, I use 10-30 Kendall Blend. Never had an issue in all types of driving/autocrossing and get it changed about every 6 months to keep the acid neutralized. I put less than 7500 miles on each car per year.

As Loren mentioned about molecules - if your car uses oil switching to full synthetic will put an end to that with those strong molecules and longer ability to change viscosity. I had a Dodge towing truck that burned 1 quart in 1000 miles with Dino but when I put in Mobil 1 it went over 5000 miles to a quart. That's impressive to me.

[jev61]

I change my POS Ford every 5K with dino, I change my Miata every 5K with full synthetic. Whatever Walmart uses as bulk goes in the Ford, whatever I find on sale goes in the Miata. You pay your money, you take your chances.

[Loren]

I've been changing my oil annually in all of my cars for the past 15 years or so. For me, that's usually anywhere from 8-12k miles, sometimes a little more. Synthetic is good for that.

I used to limit it to around 8k on synthetic until my wife bought a new MINI Cooper. It had a computer that told us when to change the oil (same as BMW uses). First oil change was right at 10k, second oil change was at 15k! It was then that I decided that if synthetic is good enough for BMW/MINI to allow an engine that's under warranty to go 15k on... it's good enough for me to run as much as that, too.

[Native]

I use synthetic (Castrol Syntec - or whatever they call it now) in my Miata and change it every 6-8 months. I drive it very little, and change it as often as I do because of the "abuse" from autocrossing. 5-6 events or twice a year. Probably very conservative.

My 4Runner gets dino and I change it every 6-8 months. I drive it very little, and change it as often as I do because otherwise I'd forget (I do it at the same time I do the Miata).

The GTI is under warranty and gets done once a year/10k miles, with whatever magical synthetic mystery lube Bert Smith uses. When the warranty is out, I'll use the Castrol and change it every 8-10k miles, which will, oddly, be at the exact same time I do the other 2 cars.

I imagine if I had an oil analysis done, I'd find that I could go longer than I do with all of them.

[lddavis91]

People who are smarter than me, more interested in doing the research and whose opinion I trust have really sold me on the Rotella T6 for most everything, I've been told its particularly good for old pushrod motors. I run it in the vette and the 302 Cobra. I change it yearly even though the vette is relegated to autocross only these days and the Cobra doesn't see all that many miles either. I'm sure it would be good for 10,000+ mile intervals since it is full synthetic. Its also cheaper than most synthetics particularly if you can find it when its on sale. I've continued to run Mobil 1 5w-30 in my Miatae as I bought a bunch of it on sale once and never ran out. My Navigator just gets the Motorcraft semi-synthetic stuff as its pretty cheap and that is what the 5.4L 32V came shipped with from the factory, so I figure its good enough for a tow rig, I change it every 5K miles.

[Solar]

I think any SAE standard oil is fine as long as it's changed regularly. Honestly how many of us have had a oil related failure in our DD or weekend auto x car ?

If I remember correctly, Rotella T6 was developed by Shell for diesel and high stress engines used for hauling heavy loads.

[Ben]

After reading this thread I suppose I change my oil a little too often, With my wrx it was about every 3k miles with full synthetic. The S2000 I was planning on changing every 5k miles or so with full synthetic.

[twistedwankel]

I think any SAE standard oil is fine as long as it's changed regularly. Honestly how many of us have had a oil related failure in our DD or weekend auto x car ?[quote]

Now don't laugh: I bought "New" one of the first FWD Iacocca "K cars" an 81 Dodge Aries. Liked the Cord grill. I actually loved that car's ability to pull me around icy corners by hitting the gas and climbing hills by zig zagging up them in the snow belt of northern OH. Open diff.

Yes I got a new auto transmission for free in 6 months. Don't ever buy the first year of a car? Otherwise a reliable car until 60k miles. The cam lobes actually wore to more round than egg. But it still ran. Why? Because Chrysler put too small of holes in the oiling system for the recommended 10W-30 oil and the winter climate. Needed 5W-20 to keep it oiled. New cam shaft with different oil wt and ran well past 100k no more problems and ran like new. So size does matter sometimes.

Was this the oil's fault? No.

[snookwheel]

Rotella t6 was recommended to me as well, something about the high Zinc content.

[shakedown067]

I run full synthetic in all my cars. Vette only gets Mobil 1 extended performance 5w30. I change it around 7,500 miles or once a year, whichever comes first. The truck get's mobil 1 high mileage and will change it every 15,000 or once a year. My wife's hyundai gets whatever synthetic is on sale, usually mobil1 0w30, and change it every 7,500-10,000. I run K&N oil filers on all of them for the ease of changing out the filter.

[BigBlue]

I've been using T6 in my Miatas since I had my first one. For what ever reason, it really quieted down my hydraulic lifter tick, so I've stuck with it. I daily that car as well as auto x in it. I end up changing the oil twice a year at around 8000-9000 miles between changes. The last time I changed the oil in the Focus I used a Warren product. I can't remember if it was Mag1 or Supertech, but it has been fine for that car's high milage (175k) engine. I do try and use a higher end oil filter and I think that has more to do with oil life than what oil you use.

[twistedwankel]

Anyone tried the recycled green product Nextgen yet?

"When you buy a new bottle of motor oil, what you're actually getting is a liquid that contains 85 percent motor oil and 15 percent additives. When that motor oil runs through your engine for a few thousand miles and gets "used," all that really happens is that additives get contaminated and useless, while the 85 percent motor oil is still there, still okay. This 85 percent is called base oil, and it can be reclaimed and turned into new motor oil."

[Vz28]

Have not tried Nextgen but since I also drive a pushrod-powered V8 car at events figured I should chime in.
My Camaro came with Mobil1 5w30 factory fill (synthetic). On the occasion where the dealer put non-synthetic or a blend in (during the early warranty years), I did notice that after repeated autocross runs and continuous idling (so hot idle) the oil pressure would be lower at idle then when I ran with the full synthetic. I used the idle pressure decline as a partial indicator on when to change the oil - and Blackstone Labs' oil analysis backed this up to some extent. I saw the same thing after track days before I took over all oil changing and used only synthetic.

So, to me, it was worth it to stick with the synthetic oil. I use mostly the high-mileage/extended performance stuff these days. As per the oil analysis and the built-in oil life indicator I only change the oil every 4k-6k, the exception being extended session track days where I may have over-heated the oil (not autocrosses). Consider that in past years this would consist of 12k+ miles a year, 12+ autocrosses a year and 4+ track days a year. Nearing 150k miles now and hot idle and high-rpm oil pressure is still close to what it was when new.

[islandmon]

Thanks for all the input. Vivek: Do you still use Mobil 1 5w30? My only concern with the T-6 is the amount and types of detergents incorporated into it as it is primarily designed for diesel fleet applications. I think I'm leaning towards Mobile 1. I think it provides the best balance of protection, power, and price for my application.

[Vz28]

Yes I still use M1 but now it is 10wSomething "High Mileage". I have not sent out for an oil analysis in a long time, guess I will do that on the next oil change.

[Loren]

Jim, read up on Zinc additives in oil. A while back (a few... maybe 10... years ago) it was mandated that Zinc levels be greatly reduced in gasoline engine oil. Zinc additives are part of what protects the interface between solid lifters and camshafts in older engines. Diesel rated oils like T6 are still chock full of Zinc and other such goodness, thus they are favored by the classic car guys. All the goodness of synthetic, plus all the goodness of old-school additives.

If Rob hooked you up with a set of roller rockers... you can probably use any oil you want without concern. As someone mentioned, thinner is better for reducing wear on cold starts. Run 0w30 (maybe even 0w20) synthetic if you can. Hell, BMW's use some exotic 0w60!

[Tim_M]

This has got to be an offshoot of the most discussed topic on the internet.

I can't say definitely of anything when it comes to what is what.

I believe in 3000 mile oil changes though using Mobil 1 and factory filters...unless it is a BMW engine that requires Castrol TWS ($14 a liter!) and 9 of those on each change...then I increase it to 5000 miles (twice as much oil than many engines I figure).

I ran 5W-30 Mobil 1 in the Corvette since day one...that engine had 55K on it when I sold it...old style LT4 with 300 degree oil temp max on road course. No problems at 7200 rpm. I always did require 150 oil temp before getting on it.

Our Subaru is similar...5W-30 M1 since day one (ok at the 1200 mile mark from the factory fill up)...now 147,000 miles. Again stress 180 degree oil temps before the fun begins. 3000 mile oil changes.

BMW has had many oil related failures (spun bearings) on M3/M5 engines. Friend lost his M3 (last generation of the 8000 rpm straight 6) just cruising down the road (never autocrossed, never tracked) using BMW factory 15,000 mile intervals. I don't agree with that...oil wears out.

I had a XL500R that uses the oil for both engine and trans and it started to get real notchy shifting after 2000 miles. Oil change made it buttery smooth. That was worth the change for the 2.5 quarts it took-what else gets notchy in an engine.

Loren commented zinc helps old style engines...I think he meant roller lifter rather than rocker-lifter is the concern. I didn't believe it until I pulled a flat tappet out of my Nova and it had concaving lifters (not yet destroyed). I then switched to the Rotella diesel oil. I'm now canning that and moving to a roller cam (more power too!).

My 2 cents, oil is cheap...engines are not if it ever comes to that. Make sure it isn't low and it has heat in it before the green flag-I'm sure you can run whatever you want for brand and be ok. I like convenience and nothing more convenient than M1 at Walmart for $24.

[shakedown067]

Yeah 15,000 miles is really pushing it, unless it's 90% driven on the highway, then maybe. All of my friends in the oil industry (a few chemical engineers to boot) run fully synthetic, and recommend 7,500 mile changes. You have to get a quality filter to boot. If it retails for less than $10, it's not a good filter. My 96 LT-1 has been running 7,500 mile changes since 97, 124,000+ miles. My old '89 chevy 305, 225,000+ miles. Didn't leak a drop of oil, changed oil every 7,500+ miles (I may have hit 9K a few times) after switching to mobil 1 in 97. Also, if I didn't hit 7,500 miles in 6 months, I changed the fluid. Moisture is a bitch, especially here along the Gulf Coast.

To error on the safe side and change every 3,000 miles, can't really argue with that logic though. You really can't go wrong there, except you're just paying into the machine.