Hey, thanks for the information, that helps!

 

This is kind of what I have always thought, but I can not find any tests that say low zinc in newer oils do OR don't cause failures in flat tappet engines. I'm not saying that I know either way. And even for high lift vehicles, all I ever read is engines blowing up before 10,000 miles and they blame the oil.

All I'm trying to say is, do we 100% know one way or the other? I don't, because I can't find any tests or studies done on it.

And, that is why I switched to an HDEO. Because I'd rather be safe than sorry. And even though I live in east Tennessee and the temps are going to be hot all summer, I felt more comfortable running a synthetic because of better start up flow.

I have seen MANY used oil analysis's using Rotella 5W-40 in MANY different engines (4/6/8 cylinder gas engines, along with many diesels). It really started turning me onto it. But I wasn't sure if it'd be a good oil that'd stand up to 'abuse' like hard revving, etc... and I finally got to see a Subaru WRX STI with an oil cooled turbo along with track runs, go for 8,500 miles. And it had amazing results. I swapped from Castrol GTX 10W-30 to this Rotella-T Synthetic 5W-40 and love it. Zero consumption, zero oil leaks. And it's getting black fast, and to me, I like knowing it's cleaning my engine. The Castrol GTX 10W-30 used to get black fast for the first 15,000 miles of me using it (blackish by 500-800 miles), and I would change it every 1000 until it started staying cleaner for longer.

Now it looks like this is picking up some more stuff the previous owner decided to leave with whatever oil they were using.

I don't want to sound like I'm trying to sell Rotella-T Synthetic, lol. I mean, I'm only recommending for the start up flow AND because it's priced excellent. $19 for a gallon around here, and that's great for an excellent synthetic. But I have seen a lot of excellent results from it no matter what it is used in.

 

Well lets think about it this way, if we need high levels of Zinc in a lube to prevent cam lobe wear, then we were depending on the "last chance barrier lube", to do all the lubricating in the high Zinc recipe oil!!!! How wise is that????

There are other barrier lubes that can do the job, like Moly, ect, so if the oil we choose says on the contaner that it's backwards compatible with previous "S" grade lubes, we should be ok with them, as their recipe has been changed with other goodies, when the P & Z were lowered.

If it doesn't say on the container, that it's backwards compatible, don't use it.

Or if we've modified the engine & are using a high lift cam & stronger valve spring rates, maybe it would be wise to listen to the cam manufacturer & use what they recommend.

It's really not a one oil fits all situations, as an oils additive package varies with manufacturer & service rating.

So if we mod an engine, or choose to use something other than the service grade & recipe the vehicle mfgr specifies for their stock engnes, then the consequences are our responsibility!!!!

If we have a flat tappet engine, the rule of thumb is to use a lube with a min of about .100 Zinc & that now generally falls into a diesel rated lube or a grade previous to SM.

But then there aren't many, or any new flat tappet engines being made now days for mass production cars, so that level of Zinc isn't needed on roller lifter, ect, engines & the extra Zinc isn't good for the cat converter on high mileage oil burning engines & becomes a pollution no-no!!!!

I can't remember right now where I read the Zinc story, but it was a few years back, when the Zinc was being lowered in our lubes.
I'll poke around in my Favorites & see if I saved it & if so I'll post the link.

 

Well, again, I mainly see ifs, ands, and buts. No offense, though. I'm just saying there isn't any studies out there THAT I CAN FIND that say low zinc does or does not affect flat tappet cams.

I read oil analysis's every day. I use Rotella because it's a great oil and has brought back perfect uoa's every time. It's not only for a safety buffer. It's because it's an excellent oil.

But, yes, zinc is being lowered. Castrol, Pennzoil, Valvoline, and any other SM rated oil that is not an HDEO will have less than 800ppm of zinc and 600ppm of phosphorous. Rotella 5W-40 is around 1200/1000 zinc/phosphorous. Usually over that.

BTW, it is wise to listen to the cam manufacturer. I recommend you to call Comp Cams (or any other cam manufacturer) and see what they recommend for their flat tappet cams. They will say an HDEO or racing oil.

 

Well, I decided on the Rotella T 15W40, and I am using Havoline 10W40 in the 96. Thanks for the great info!!

 

Good choice, Tees.

 

I'd go with the Rotella-T in both trucks. The Havoline won't be any better for zinc/phosphorous than your average 5W-30 Pennzoil, Castrol, etc. That is, if you are choosing oils with high z/p levels.

EDIT: Oh, 96, So I'm assuming you are a roller engine. Any oil will be fine, and Havoline seems to show good results if changed in the correct OCI.

 

I just want to clarify that it is not the zinc that kills cat converters, but phosphorus. Anyone care to guess what the P in ZDDP is? P in a chemical compound with other metals is key to extreme pressure lubrication. The stinky part of gear oil is a sulfur-phosphorus compound. That additive cannot be used in engines because the moisture in blowby would make it highly corrosive to bearings. TCP is an "ashless" extreme pressure additive in some aircraft oils because of Lycoming cam and lifter wear problems. Even 15W-50 synthetic blend cannot protect those parts without EP additive.

Jim

 

Does the 300 have roller lifters? I thought I went through that in an earlier thread, wondering if my '95 had rollers, and the answer was 'No rollers'.

BTW - I use either RTS 5-40 or M1 10-40 in my 300.

 

post pics!

 

Is that engine made to run on unleaded gas? If not, I would be concerned about changing that first.

 

No need.

ALL 1973/79 trucks were designed to run on ANY kind of gas at that time (regular leaded or unleaded) where applicable. After 1975, some light duty trucks could only run unleaded.

 

Well, I could only go by what the manual states.

Here's what my 1977 owner's manual states:
The engine in F-100 vehicles and certain 150,250,350 vehicles, equipped with catalytic converters are designed to operate on UNLEADED FUEL ONLY. On F-150, F-250, and F-350 vehicles, the engines are designed to operate on "regular" (leaded) or "low lead" gasoline.

This tells me that a cataylist engine must run UNLEADED FUEL ONLY and a non catalyst engine runs on leaded gas. It doesn't mention anything about a non catalyst running on unleaded gas.

 

Yes, catalytic converter equipped vehicles must use unleaded gas, otherwise the lead will kill the catalytic converter. Remove the converter and it could use leaded. Many people did this back then when leaded was still available. Back way when, a buddy stopped by in a brand new 1979 F250. We cut the cat off and put dual exhaust on it. Then we took a cold chisel to the restrictor in the filler neck so he could put leaded gas nozzles in it.

I have a 1978 F150 that could use regular leaded...it's been running unleaded for its entire life. It's fine. No harm, no foul.

 

I think the point of the last three posts is that by the mid-1970's all gasoline engines had hardened valve seats and low compression, so there is no "converting" them to use unleaded fuel.

Jim