Why is this?

[wwoodrow]

My old 424 IH gas burner burned oil for years and would foul plugs within a couple of hours of hard use. I used the 30 wt. recommended by the manual. I finally decided to try 10w40 as " what could it hurt"? The result- it still seems to use as much oil but never fouls a plug anymore . Why is this ?

 

[rustred]

post a pic of the plugs with the 30wt oil, and a pick of the plugs with the 10-40 oil. engine temperature and load plays into plugs condition. you would need to work it the same amount of time like a day or so with both oils and using the exact same plugs. then read your plugs. to much unknown here. also new clean oil is not like old worn out oil contaminated with gas and carbon. plus the tune up spec's would all need to be at factory spec's for optimum performance. points, timing and carb setting, and clean air cleaner.

 

[Jim Becker]

Along the line of rustred's questions, what sort of 30 weight oil were you using? Was it ND30 that is usually labeled for air compressor use?

 

[wwoodrow]

Along the line of rustred's questions, what sort of 30 weight oil were you using? Was it ND30 that is usually labeled for air compressor use?

The 30 weight varied from valvoline, havoline, Quaker State, NAPA store brand. All were automotive oil. I have used tractor long enough now with both weights of oil to be certain that the only variable is the oil. I operated both oils under various work loads, temperatures, condition of points, plugs, air filters, etc.

 

[Janicholson]

The 30 weight varied from valvoline, havoline, Quaker State, NAPA store brand. All were automotive oil. I have used tractor long enough now with both weights of oil to be certain that the only variable is the oil. I operated both oils under various work loads, temperatures, condition of points, plugs, air filters, etc.

Modern multi wt. oils have viscosity stabilizers and temperature related conditioners that straight wt. oils lack. Jim

 

[wwoodrow]

Modern multi wt. oils have viscosity stabilizers and temperature related conditioners that straight wt. oils lack. Jim

Sounds very plausible. Thanks.

 

[rustred]

The 30 weight varied from valvoline, havoline, Quaker State, NAPA store brand. All were automotive oil. I have used tractor long enough now with both weights of oil to be certain that the only variable is the oil. I operated both oils under various work loads, temperatures, condition of points, plugs, air filters, etc.

still like to see the spark plugs from each oil.

 

[wwoodrow]

still like to see the spark plugs from each oil.

It would be intersting but I dont plan to put anymore straight 30 wt. in it to do the comparison. They were very oily. I may pull a plug now just to look at it. I really have not had the need to pull one since I have been running the 10w 40. I may go to 15w 40 as I now see that may tractor folks are running it in older tractors.

 

[Texasmark]

It would be intersting but I dont plan to put anymore straight 30 wt. in it to do the comparison. They were very oily. I may pull a plug now just to look at it. I really have not had the need to pull one since I have been running the 10w 40. I may go to 15w 40 as I now see that may tractor folks are running it in older tractors.

I'll bet you will pick up some more additives doing that since 15W-40 is a HD oil made specifically for heavy duty diesel engines, thus the added additives....yes its S and C rated and you can run it in your old PU truck if you have one too.

 

[wwoodrow]

I'll bet you will pick up some more additives doing that since 15W-40 is a HD oil made specifically for heavy duty diesel engines, thus the added additives....yes its S and C rated and you can run it in your old PU truck if you have one too.

I actually do have an old pickup. I have recently quit using it as a daily driver and it is relegated mostly to farm duty. It has 505,000 miles on it. I have run 10w30 in it for years . [ 2002 model F150 fx 4 ] I have considered a heavier oil but decided against it due to possibly it not allowing the thicker oil to flow well through the tight tolerances of the engine.

 

[bc]

It may just be me but I'd think an engine with 505,000 miles probably doesn't have any more tight tolerances. I've run 10 w 40 in my f150 with 157k miles and would consider 15 w 40 without a problem.

 

[Texasmark]

I actually do have an old pickup. I have recently quit using it as a daily driver and it is relegated mostly to farm duty. It has 505,000 miles on it. I have run 10w30 in it for years . [ 2002 model F150 fx 4 ] I have considered a heavier oil but decided against it due to possibly it not allowing the thicker oil to flow well through the tight tolerances of the engine.

My last Ford was a 1988 F150 SLT or whatever that upgrade acronym was. It had Velour Captains chairs and I didn't want to stink it up so I drop dead, quit smoking after more than 30 years on the spot and haven't touched one since. It was a 5 liter V8 and I ran 15w-40 in it since I had plenty of it around and the Autolite FL-1 filters as all my Ford tractors used both.
As BC stated, probably no tolerance would still be in spec......lotta miles on that truck.

 

[used red MN]

It may just be me but I'd think an engine with 505,000 miles probably doesn't have any more tight tolerances. I've run 10 w 40 in my f150 with 157k miles and would consider 15 w 40 without a problem.

If the oil is being maintained(changed enough) to stay within the engines required “design lubrication needs” and the contamination in the oil is within spec the bearings are not wearing, the load is carried by the oil film. Not wearing at all is probably going a bit far, but wearing to a somewhat higher level than that of water running over a rock.
To the OP, my guess as I think has been said, it is an additive in the oil that is now keeping the plugs from fouling. I think they have additives that are for minimizing carbon build up. I can see where this might keep the residue from building up on the plugs. Have you used different brands of 10w40 with the same results?

 

[wwoodrow]

If the oil is being maintained(changed enough) to stay within the engines required “design lubrication needs” and the contamination in the oil is within spec the bearings are not wearing, the load is carried by the oil film. Not wearing at all is probably going a bit far, but wearing to a somewhat higher level than that of water running over a rock.
To the OP, my guess as I think has been said, it is an additive in the oil that is now keeping the plugs from fouling. I think they have additives that are for minimizing carbon build up. I can see where this might keep the residue from building up on the plugs. Have you used different brands of 10w40 with the same results?

Yes, I have used different brands but stay with Mobile, Valvoline, or similar quality[ hopefully ] oils. I have not poured any Janoco into it yet!!

 

[560Dennis]

What was the manifold vacuum of the sae 30wt compared to the 10w40 wt .

 

[used red MN]

Yes, I have used different brands but stay with Mobile, Valvoline, or similar quality[ hopefully ] oils. I have not poured any Janoco into it yet!!

Just thinking that if you have only ran one brand of 10w40 that it may have a particular additive that keeps the plugs from fouling. This is all speculation.

 

[wwoodrow]

What was the manifold vacuum of the sae 30wt compared to the 10w40 wt .

I have no idea.