1980 F350 4X4 C6 Project

[Gary Lewis]

Thanks for the insight into fluids for transfer cases and differentials.

What about engine oil recommendations for the 400? I read about zink levels and oil pressure issues in the 400 so I am curious what others are running.

Is your engine new? It is on break-in of the cam that the most concern is for additives. But you still need to run some zinc for the cam even after break-in.

I’m running Brad Penn oil, but that’s probably overkill. However, since I have quite a bit of it that’s what I’m running. I think many others are running diesel oil, but I’ll let them speak to that.

On the oil pressure, if you are building a 351M or 400 there are mods that can be made to bring the pressure up. Go to Documentation/Engines/351M & 400 in the menu for a discussion of that.

[Atlas75]

Is your engine new? It is on break-in of the cam that the most concern is for additives. But you still need to run some zinc for the cam even after break-in.

I’m running Brad Penn oil, but that’s probably overkill. However, since I have quite a bit of it that’s what I’m running. I think many others are running diesel oil, but I’ll let them speak to that.

On the oil pressure, if you are building a 351M or 400 there are mods that can be made to bring the pressure up. Go to Documentation/Engines/351M & 400 in the menu for a discussion of that.

The engine is not new. Supposedly rebuilt but I have no idea how long ago, what was done to it in the rebuild, or who did it. I just remember reading you need a certain level of zinc in the oil if you have flat tappet lifters?? I’m not sure what type of cam and/or lifters are in this engine.

[ArdWrknTrk]

The engine is not new. Supposedly rebuilt but I have no idea how long ago, what was done to it in the rebuild, or who did it. I just remember reading you need a certain level of zinc in the oil if you have flat tappet lifters?? I’m not sure what type of cam and/or lifters are in this engine.

Be glad you don't have solid lifters!

I can't speak to a 400* specifically, but I always use diesel oil.

It has more detergent and a longer OCI.

Now that diesels too are using catalytics you aren't going to find the same elevated lives of ZDDP in CI oils that you used to.

But if you are that concerned you can add some (as long as you don't have a catalytic converter)

Because replacing those every six months when they get poisoned will get expensive quickly.

[Gary Lewis]

The engine is not new. Supposedly rebuilt but I have no idea how long ago, what was done to it in the rebuild, or who did it. I just remember reading you need a certain level of zinc in the oil if you have flat tappet lifters?? I’m not sure what type of cam and/or lifters are in this engine.

The biggest problem on the oiling system of the M-block engines is that it puts way too much oil to the #1 main bearing, thereby leaving too little for the lifters, and especially those on the driver's side which get their oil after the #5 main.

Tim Meyer told me he's turned an engine on his dyno w/o a pan and he could see lots of oil escaping from the #1 main, but not nearly as much from the others. So he came up with some mod's that make a big difference. The first mod is to the oil passage to #1 main, as shown below. The second is his own cam bearings that restrict the flow to the cam, thereby leaving more for the lifters.

The combo of those two works well. He built my engine and then ran it on the dyno. After warming it up and then doing six pulls to 5500 RPM it idled at 20 PSI of oil pressure.

 

[Atlas75]

The biggest problem on the oiling system of the M-block engines is that it puts way too much oil to the #1 main bearing, thereby leaving too little for the lifters, and especially those on the driver's side which get their oil after the #5 main.

Tim Meyer told me he's turned an engine on his dyno w/o a pan and he could see lots of oil escaping from the #1 main, but not nearly as much from the others. So he came up with some mod's that make a big difference. The first mod is to the oil passage to #1 main, as shown below. The second is his own cam bearings that restrict the flow to the cam, thereby leaving more for the lifters.

The combo of those two works well. He built my engine and then ran it on the dyno. After warming it up and then doing six pulls to 5500 RPM it idled at 20 PSI of oil pressure.

Well I finally had a chance to change the oil today. What came out was definitely dark in color. I’m concerned about the oil pressure though...and not in the way you might think. There are two oil pressure gauges in this truck. The factory one in the dash and an aftermarket one mounted under the dash. Before the oil change the factory needle was between the “R” and the “M” and the aftermarket read 60 psi. After the oil change the factory needle is between the “M” and the “A” and the aftermarket now shows 70 psi. Is that even possible? That seems really high. If something is wrong...what would it be?

[Gary Lewis]

Well I finally had a chance to change the oil today. What came out was definitely dark in color. I’m concerned about the oil pressure though...and not in the way you might think. There are two oil pressure gauges in this truck. The factory one in the dash and an aftermarket one mounted under the dash. Before the oil change the factory needle was between the “R” and the “M” and the aftermarket read 60 psi. After the oil change the factory needle is between the “M” and the “A” and the aftermarket now shows 70 psi. Is that even possible? That seems really high. If something is wrong...what would it be?

Yes, that's possible for a couple of reasons. First, if you went back with a heavier weight oil than was in it. Do you know what was in it and did you put a heavier weight oil back in?

Second, because a multi-viscosity oil will give higher oil pressure when it is new. The reason for that is that the high end of the viscosity range is achieved with long polymers and they tend to get sheared over time as they pass through the oil pump, so the viscosity then comes down.

[Atlas75]

Yes, that's possible for a couple of reasons. First, if you went back with a heavier weight oil than was in it. Do you know what was in it and did you put a heavier weight oil back in?

Second, because a multi-viscosity oil will give higher oil pressure when it is new. The reason for that is that the high end of the viscosity range is achieved with long polymers and they tend to get sheared over time as they pass through the oil pump, so the viscosity then comes down.

I have no idea what was in it or when it was possibly changed last. The only thing I know is that it was pretty dark and the oil filter had some rust on it (and it was a pain to get off ).

I put in a 10w-40.

70 psi just seemed high to me, especially at idle after it warmed up a bit. I guess we'll see what happens over time.

[Gary Lewis]

I have no idea what was in it or when it was possibly changed last. The only thing I know is that it was pretty dark and the oil filter had some rust on it (and it was a pain to get off ).

I put in a 10w-40.

70 psi just seemed high to me, especially at idle after it warmed up a bit. I guess we'll see what happens over time.

70 PSI is high, especially for a 351M or 400 as they are notorious for having low oil pressure. Do you know the history of the engine? Like, how many miles are on it? From the early pics you posted it doesn't look to have been rebuilt.

As said, the M-block engines are notorious of low oil pressure. That has to do with the way the system was designed, which you can read about on the page at Documentation/Engines/351M & 400 and then the Oiling System tab, which is where the drawing below came from.

Dad's well-worn 351M idled at 10 psi after being truly warmed up. Rusty's was a bit higher as it had been rebuilt recently, but was still only like 15. So 70 is quite high, and I don't know why. But I worry that the engine might be full of gunk and that may be blocking some passages. However, as you can see in the drawing, the oil pressure pickup point is after everything but the lifters on the driver's side, so if you have that much pressure there everything else must be getting oiled quite well.

But I'd watch the color of the oil to see if it turns black very quickly as you may be cleaning up the engine. And watch the oil pressure as it will naturally come down as the oil gets used some.

[Atlas75]

70 PSI is high, especially for a 351M or 400 as they are notorious for having low oil pressure. Do you know the history of the engine? Like, how many miles are on it? From the early pics you posted it doesn't look to have been rebuilt.

As said, the M-block engines are notorious of low oil pressure. That has to do with the way the system was designed, which you can read about on the page at Documentation/Engines/351M & 400 and then the Oiling System tab, which is where the drawing below came from.

Dad's well-worn 351M idled at 10 psi after being truly warmed up. Rusty's was a bit higher as it had been rebuilt recently, but was still only like 15. So 70 is quite high, and I don't know why. But I worry that the engine might be full of gunk and that may be blocking some passages. However, as you can see in the drawing, the oil pressure pickup point is after everything but the lifters on the driver's side, so if you have that much pressure there everything else must be getting oiled quite well.

But I'd watch the color of the oil to see if it turns black very quickly as you may be cleaning up the engine. And watch the oil pressure as it will naturally come down as the oil gets used some.

I don’t know the history of the engine. The guy I bought the truck from said it was rebuilt before he got it and he hadn’t owned it very long. With no receipts or documentation, who knows what rebuilt means. I did manage to find out who owned it before the guy that I bought it from. Maybe I should try to contact him and see what he knows...

[Gary Lewis]

I don’t know the history of the engine. The guy I bought the truck from said it was rebuilt before he got it and he hadn’t owned it very long. With no receipts or documentation, who knows what rebuilt means. I did manage to find out who owned it before the guy that I bought it from. Maybe I should try to contact him and see what he knows...

I would ask. It can't hurt. All he can say is "I don't know". But he might have some good info.