Oil Choices....

[chris young]

You all got me curious, so, I did a pile of reading, since I have no other way to make an informed decision for myself. I just finished this http://www.bobistheoilguy.com/motor-oil-101/ All 10 pages! very informative.

Now I'm even more confused. It wasn't entirely clear to me, but I get the impression that the lower ZDDP numbers in the new oils are because they have developed other additives to replace it, so a new high quality oil with lower ZDDP may not be a bad thing. I'll re read when I get a chance and see what else I can dig up. The other thing that has me confused is recommending a xW50 oil when our motors typically operate at lower temps which would call for lighter, not heavier oil. (That's not directed at you Micheal, I've read it on other forums as well) My guess is that the lighter weights have less ZDDP? Apparently 50 isn't much thicker than 30 at operating temp anyway so I guess it's not really much of an issue.

After getting more informed I'm even more confused

This summer, unless I learn something more I think I'm going to go for a light synthetic and try the 10psi per 1000RPM rule to match. (the linked article states that you are trying to get approx 10psi/1000RPM in order to get the maximum flow of oil)

[92SupraComp]

guys, DO NOT OVER THINK THIS! its oil. As long it does its job we are good. I have been running 10w-30 Mobil 1 oil for a few years and everything has been fine. My Supra and CC BOTH have 80's ford 351 Windsors. Only diff is my Supra has the electronic ignition, Holley 4010 carb, and gt40 heads... They both have flat tappet cam shafts which why they need the higher ZDDP. Yes the motor do run cool compared to their normal closed loop temp. (I put a 160* t-stat in my comp, runs a strong 170*, much closer to normal operating temp) My comp has always run a min of 35psi to a max of 50 psi on the oil. My CC runs min of 15psi to 60 psi when hot. But almost 80psi when cold and around 15 psi hot at idle. Same engine, very different pressures, but SAME OIL. The CC has around 850 hours, the Supra has at-least 1800+ hours... (was used a bunch up until we moved to texas)

[michael hunter]

The weight and amount of ZDDP has nothing to do with oil pressure. First lets look at the multi viscosity versus straight weight oils.
Straight weight is just that 50 weight is 50 all the time so a cold engine will have more difficulty turning with the thicker oil but it will protect better when hot. Put in 15 weight and it will turn over faster but it will be too thin to protect the engine at normal operating temp. The reason multi weights are better is they conform to all engine temps . When cold a 15w50 will act like 15 weight oil allowing easier starting as the engine heats up it will provide the protection of 50 weight oil . Synthetics don't thicken or thin out with temperature this is why Mobile 1 will pour like its 80 degrees even when its -0. Oil pressure has more to do with bearing clearances, as the bearings wears the clearances get larger and the oil pressure gets lower. Thicker oil will fill that gap when cold and raise pressure but it will thin out as it heats up and oil pressure will get lower. The reason you need ZDDP is to lubricate the surface of the lifters and camshaft on flat lifters only.You need a lubricant that will protect at extreme pressure because of the valve spring load on the lifter. Most newer engines have roller lifters the high ZDDP content is not required. Using insufficient oil will not reduce oil pressure but it will eventually flatten the cam lobe and damage the lifter. It won't happen immediately it is a long slow process that can take years depending how poor the oil is. Most people only change the oil once a year. I try to use the best products I can find the extra cost is minimal.

[MJHKnox]

LOL. Yeah, I might have gone a little overboard, but I know there are some new guys on this board that may not know, and I wanted everyone to know that this was more than just an opinion. It's nice to know that someone is commenting based on experience and not because "my daddy always used pennzoil..."

+1 on that

[DAFF]

The weight and amount of ZDDP has nothing to do with oil pressure. First lets look at the multi viscosity versus straight weight oils.
Straight weight is just that 50 weight is 50 all the time so a cold engine will have more difficulty turning with the thicker oil but it will protect better when hot. Put in 15 weight and it will turn over faster but it will be too thin to protect the engine at normal operating temp. The reason multi weights are better is they conform to all engine temps . When cold a 15w50 will act like 15 weight oil allowing easier starting as the engine heats up it will provide the protection of 50 weight oil . Synthetics don't thicken or thin out with temperature this is why Mobile 1 will pour like its 80 degrees even when its -0. Oil pressure has more to do with bearing clearances, as the bearings wears the clearances get larger and the oil pressure gets lower. Thicker oil will fill that gap when cold and raise pressure but it will thin out as it heats up and oil pressure will get lower. The reason you need ZDDP is to lubricate the surface of the lifters and camshaft on flat lifters only.You need a lubricant that will protect at extreme pressure because of the valve spring load on the lifter. Most newer engines have roller lifters the high ZDDP content is not required. Using insufficient oil will not reduce oil pressure but it will eventually flatten the cam lobe and damage the lifter. It won't happen immediately it is a long slow process that can take years depending how poor the oil is. Most people only change the oil once a year. I try to use the best products I can find the extra cost is minimal.

If this is the case I am going to try an experiment on the plow trucks this winter and run a synthetic 15w 40 in the main truck. Some mornings in the thick of the cold season temps will be below zero (F) in the wee hours of the morning. Having any advantage of a insured start up is well worth it. Plugging in the truck works too but I reserve that when the temp dips -15 below.

As for the boat ended up getting some 15w40 AMS Oil from a friend. Might take him up on doing some oil analysis over the up coming year or two on the Launch just for fun too.

[michael hunter]

I would go with a 0w30,0w40,5w30 or 5w40. The only reason I use the 15w50 is it is the recommended weight for use in older flat lifter engines because of ZDDP content. Do the pour test , next time it dips below 0 put out a qt of conventional and synthetic overnight then pour them in the morning.

[haugy]

Pfffft you guys don't know anything.


I use Chuck Norris' sweat for my oil. The thing runs meaner, cleaner, and can actually punch you if you make fun of it.

[mlaosa]

I'm a senior master ford tech and agree with most of you-- especially Michael hunter. I run 5w-30 syn. blend in my conbrio but it has a 1991 PCM 351. In my career I've seen newer engines have very close tolerances compared to older engines, meaning smaller oil passages pushing oil throughout the engine. I've personally seen engines smoked due to someone just deciding to choose a much thicker oil because they think it's "better". NOT!! Now that being said, I definitely don't think even newer marine engines are nearly as close tolerance as autos, but one thing you have to remember is weather a 302, 351, 454 or whatever your running, our boat engines are usually under much higher load being we don't have a 5 speed transmission behind it. My personal opinion is choose whatever you choose and stick with it. But do your research before you decide to change the weight of oil. And more than that--- why would you want to change what the manufacturer recommends?? Just my .02

[Cusefan78]

I agree with 92 comp the one you want is Mobile 1 15w50 that weight has the zinc content for the older engines. I change every 50 hours with a Mobile 1 or K&N filter. Some guys are using Rotella T diesel oil be sure to check the zinc levels in the current formula .I read they have lowered the content in the present formula. I buy the oil at Walmart 24.95 for a 5qt jug the filters come from eBay motors. Make sure they offer free shipping or you will pay as much for shipping as the filters.

is this fall I was able to get oil at wholesale pricing through a client so I bought a few cases. After a ton of research I found that the Canadian brand of rotel has the original high zddp content. Canadians can get it at any automotive store. those of us that live in the us have to get it ordered in.

[cjtpilot]

I like Lucas oil myself, and substitute a quart of Marvel Mystery Oil in.