what's the scoop on using synthetic oil in slant 6???
advantage? disadvantage? bad idea?

Same story as using synth oil in any other engine.

Chief advantages: Much lower "pour point" temperature for easier starting and faster lubrication on cold starts. Less tendency to form sludge. Better lubricity.

Chief disadvantage: Higher cost. You can spend anywhere from $3 to $15 on a quart of synth oil. Thread Here.

Note that the present "regular" Mobil-1 is not nearly as good a choice for our cars as the Mobil-1 Extended Performance. That's because the plain Mobil-1 has recently been reformulated without certain Extreme Pressure additives that work to combat sliding friction (e.g. lifters against camshaft, fuel pump lever against eccentric, etc.). Since all modern engines use roller lifters and electric fuel pumps, this particular kind of friction generally isn't found any more. But, that kind of protection is very necessary in older engines. The regular Mobil-1 won't burn up an older engine, it's just that the Extended Performance stuff will work better.

RedLine is certainly terrific oil. Perhaps if I had a professional race car with an engine worth five figures, I'd use it. Other than that...not cost-effective. (I have happily used RedLine's transmission and gear lubes).

I avoid Amsoil products just as religiously as too many of their dealers push it. No API approval except in their inferior 2nd-line engine oil. Also poor results when tested independently. Also twice the price of Mobil-1, with poorer availability.

In the end, remember that even the cheapest name-brand conventional oil you can buy today is hugely superior to what was available when our engines were new.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Mobil 1 synthetic extended performance is $24/5quart jug at walmart, thats $4.80 a quart. Says 15,000 mile change intervals. Don't know about leaving it in that long, I'll probably run mine 4000 or 5000 miles, maybe longer.

Strictly going by the rating if you compare price/mileage ratio its not that bad. Not sure what the offical, scientific judgment is on terms of how much longer synthetic lasts though vs dino.

I use synt 10-30. great! I've used synt 5-40 and regular 15-40. I have to say that the 10-30 i'm using now seems to make my mill very happy. As a matter of fact I put 1000 miles on her this weekend cruising @100 and I had a very low .25 liters oils consumption (normal for that high revving constant speed according to my calculations). I change my oil every 3 months no matter what mileage I put on it (of course, If I put 4k miles on her before the 3 months I change it anyway) and I ALWAYS use a molykote AF4 anti friction additive. Call me stupid, I prefer to have my engine safe and sound rather than squeeze it for saving 2 dollars now and have a major headache later. Same goes to carburetion... I tune it a li'l bit on the rich side especially being the wotter I am.

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Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

I use Rotella T diesel oil in my slants. Managed to find it in 10W-40. Expensive but I've heard that it is grest on loder engines that still have all of the sliding, shearing, and rubbing parts.

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

Rotella is much cheaper than any other syn oil though. I've seen it for about $10/gallon at Advance. I almost used it on my VW as its approved, but went with the Mobil 1 0-40 which was specifically stated as approved. Since sludging was a problem in that engine, we've always run syn in it from the day we got it.

MJ

sludging starts the minute you try to squeeze 10 miles more from that oil change....

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Juan Ignacio Caino

Please use e-mail button istead of PM'ing. I do log in sometimes but I'll be answering quicker thru e-mail.

Well on the 1.8T there was actually a recall on it from VW. They mandated the use of syn oil and a larger filter than had been supplied. Dealers had just been using regular oil and so many of the 1.8Ts were dying prematurely even when changed on the regular intervals. I think I recall reading it had something to the do with the oil pan becoming too shallow in spots when it was modified to accomodate a suspension change VW made. But yeah, sticking with the time/distance requirements is a no-brainer (you got none if ya don't do it?!)

MJ

As far as Rotella goes, there are alot of guys that are switching away from it for the heavy equipment. They claim a lot of people are losing wrist pins around 100k miles. (not sure how valid that claim is, just word of mouth) We still sell tons of it at work, but we've also been selling quite a bit of Delo 400, by Chevron.

I use Napa fleet oil. Its diesel oil, 15W-40. Made by Valvoline.

I was going to post along the lines of "I used to use Rotella, too, before I started reading www.bobistheoilguy.com ", but didn't get around to it.

DS (oops)

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I just went ahead and bought some Royal Purple 10w-30 and im going to see if all the hype and articles are worth the extra money and maybe some free extra horsepower : )

Don´t know about engines, but tranny, and rearends move so much easyer with synthetic oil.

Now, I have to hold the brakes when at a redlight...

for what it's worth, grassroots motorsports ran an article a few years back running back to back dyno tests after changing one oil reservior at a time (engine, then trans, then rear diff) and refilling them with redline (i think.) they actually claimed a few horsepower overall. i believe most gains were from the gearboxes.
i have personally used redline to improve shifting 5-speeds in the past. no experience with the amsoil (amway?) i think most manufacturers are pushing the synthetic blends these days.

-james

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Some of those tests don't control the variables very accurately...............

Was it the oil change or the fact that the parts have warmed up between tests (warmer parts, thinner oil, less drag.................)

Unless you take a 30 minute drive, test, change, same drive,test,change,same drive,test......... conditions aren't exactly the same......

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes