There are many myths surrounding synthetic oil. I recently found from an old time speed shop builder that synthetic was developed for jets in the '50's to keep the engine oiled in HIGH G situations.I was told that they are of no real benefit unless you're pulling around 2 G's.
__________________
gearhed1971
1973 f100-390 4wd
1963 falcon-under construction
1951chebby special deluxe(for sale)-SOLD!!!
daily beater poontang sunfire
The main real world benefits of synthetic oils are:
cold start up flow, namely in the sub-zero temps, but even in just freezing weather, synthetics have their place.
Extended oil change intervals.
High performance apps (especially in anything with oil cooled turbos)
Otherwise, I run synthetic Rotella over conventional soley because it comes in 5W-40 vs the 15W-40 (I want the 40, but not the 15W at start up). 5W-40 isn't really much thinner at 40C, but I know when it gets to 0C and better, it will flow better than conventional 15W-40. So, those reasons, and it's so cheap. Not much more than your average conventional.
But, yeah, conventional oils these days can take damn near anything. But I don't trust SM rated conventional oils in my flat tappet cam set up. Sorry, I know it's debatable and people will say they have ran theirs for this and that... but I just don't trust the 800/600 zinc/phos ratings for my old truck. Gimme an HDEO. BTW, Mobil1 will also adhere to 800/600 zinc/phos. So, I don't really know if it's the best thing for your old 302. If you had a roller 302, I'd say use whatever you want, but even with our low lift flat tappets, I still want some extra anti-wear in the zinc and phos department.
__________________ 1986 F-150 5.0 EFI XLT Lariat 4x4 NP435/NP208/9" 3.50
"Custom Exhaust" and leaf spring overloads
31x10.50 15" Nothing special, but it's a damn good truck.
If you've ever seen the inside of an engine that has had only synthetic oil vs one that has had conventional oil, the benefits are immediately apparent. Even a well maintained and good conventional oil will leave a reddish brown film on all of the internals. Synthetics (at least Mobil 1) does not. My Corvette has 100k miles on it and it's had Mobil 1 in it since day one. You can pull a valvecover, intake, or oil pan, and look around and there is nothing to betray it's mileage. Everything looks like it did the day it came out of the factory.
As far as synthetics being "safe," of that I have no doubt. The problem is that often times when an engine has been run a long time on conventional oil, the seals deteriorate but they don't leak terribly much, if at all, because over time, sludge builds up around the seals and serves the same purpose. When you put a synthetic in there and it slowly cleans out the sludge, then the leaks develop. This is nothing new. My dad tells a story of a guy he went to college with who thought he would do his sports car a favor and use that "heavy duty" oil. Turns out HD, which he thought meant heavy duty, really meant high detergent. The engine didn't leak a drop of anything until he switched to HD oil then it leaked from everywhere.
Synthetics have excellent sludge fighting abilities, excellent cold pour properties, and excellent lubrication properties. Anybody who wants to argue that point has obviously never seen a side by side comparison of a synthetic vs non synthetic motor. Now is it enough to matter? Maybe an engine will run for 300k miles on regular oil and 350k on synthetic. Most people don't have a vehicle for that long so it really doesn't matter.
Interesting point, the LT1 engine in the Corvette was spec'd for synthetic oil. The LT1 engine in the Camaros and Firebirds did not. The engines were basically identical, the only reason was that the Corvette did not have an oil cooler, whereas the Camaro / Firebirds did. It wasn't so much an anti-wear call as it was a high temperature call. The oil temps in my Corvette stay below 200 most of the time, but if I start beating on it, such as hot lapping it at the track, or running a road race, it'll quickly push 300. Normal oils start breaking down very quickly at high temps.
As far as the Amsoil point, I've heard many great things about it. The only reason I use Mobil 1 over Amsoil, is not that I beleive it's better, it's a matter of what's convienent. I don't know of anywhere locally that I can buy Amsoil. Amsoil may be better than Mobil, but Mobil is better than most and is readily available where I live, so that's what I use.
BTW, Mobil, or any synthetic probably won't be the best for a flat tappet cam. Being said, however, this truck is not something that I'm gonna be putting 20k miles on per year. As soon as I can afford it the flat tappet cam is going the way of a roller along with a supercharger.
Why would any synthetic not be good for a flat tappet cam?
Apparently flat tappet cams wear at a faster rate when used with oils that meet modern standards for having less particulates (mainly zinc I believe). Since almost any synthetic is going to meet all of these modern "clean oil" standards, that makes them not good on flat tappet cams, or so that's the theory.
Basically what has probably happened is that since nothing uses a flat tappet cam anymore, nobody really thought to see how these new standards would affect older engines. We're living in a world where people just throw things away when they get more than 30 days old anyway, so why bother to see how it works on something old? I mean it's old, it's obviously junk anyway right?
I am not aware of any synthetics that are designed specifically for flat tappet engines and have the extra zinc. That doesn't mean that they don't exist, just that I don't know about them.
This is direct from Mobil's website:
Quote:
Answer:
For older, flat tappet engines where wear may be more of a concern, we offer a number of oil products which are higher in phosphorus than API SM/ILSAC GF-4 oils. These include Mobil 1 15W-50 (1,200 ppm), Mobil 1 0W-40 (1,000 ppm) and Mobil 1 High Mileage 5W-30, 10W-30 and 10W-40 (900 ppm). For all newer engines and flat tappet engines in normal service, API SM/ISLAC GF-4 oils are preferred for better fuel economy and for the protection of catalytic systems with lower phosphorous (800 ppm).
I have been running 10w-30 full synthetic (Any major brand) with an Fl-1A in my 74' F-100 302 with 80k orig miles. Used to drive the truck year around and when I bought the truck the engine was sludgy from sitting for a lot of years. I also drove it all year around and in the winter the full synthetic helped a lot. Now I don't drive the truck often but I still have full syn in it. next oil change I will be putting in Motorcraft synth blend 10w-30. Despite being over 35 YO the engine still runs great and doesn't use or leak much oil.
I believe Rousch has a synthetic oil out that has more zinc and phos but it is crazy expensive.
Mobil1 has a diesel synthetic with levels of ZDDP that are elevated from the levels found in the API certified gasoline oils. The Mobil1 race oils have even higher levels than the diesel oil:
Synthetic HDEO's usually offer around 1200/1000 ppm of zinc/phos respectively. I didn't know if you said synthetics weren't good because they are 'synthetic', or if you didn't know of any synthetics that had lots of good zinc/phos numbers.
That's why I use Rotella-T 5W-40. Also probably the best synthetic HDEO at the moment.
Mobil1 0W-40 has 1000ppm of zinc like you mentioned, as does Castrol Syntec 0W-30... another great oil. But, I figured why not go all out, get the stoutest oil (HDEO) for half the price?
__________________ 1986 F-150 5.0 EFI XLT Lariat 4x4 NP435/NP208/9" 3.50
"Custom Exhaust" and leaf spring overloads
31x10.50 15" Nothing special, but it's a damn good truck.
This forum is owned and operated by Internet Brands, Inc., a Delaware corporation. It is not authorized or endorsed by the Ford Motor Company and is not affiliated with the Ford Motor Company or its related companies in any way. FordŽ is a registered trademark of the Ford Motor Company.
