Oil changes, is the oil "consistency" different drained from sump vs. engine bottom?

[H.G.P.]

Upon changing oil, is the oil "consistency" ("uniformity"), which drains from the sump, different than the oil drained from the engine bottom?

(Mine appears thinner from the sump...edit.., by "sump" I mean the oil tank under the rear fender)

Thanks

[RoninLB]

Originally posted by H.G.P.


(Mine appears thinner from the sump...

Uh oh

[Jim Sims]

Fuel dilution of oil? Is an MFI system fitted? Jim

[Todd Simpson]

You shouldn't have any difference, the oil is constantly circulated between the engine and tank. Even fuel dilution would show up in both places.

Tell us more about the condition of the engine, fuel system, other details. I think it's either an illusion or something to do with the temps being different between the engine and tank if the car sat a little while after running.

[H.G.P.]

Originally posted by Jim Sims
Fuel dilution of oil? Is an MFI system fitted? Jim

It has much of the original MFI parts (crankase vent stuff behind the airbox), and the two fuel outlets, but not using the return line. But it's running with carbs currently.

Fuel delivery is Carter/Federal Mogal pump, with a Holley preformance regulator, The only thought could be two things?

1. Could the fuel pressure be too high? But it runs great, and idles terrific after warm-up.

2. And/or I like to prime the engine before (pump the accelerator a few times, before cranking to pressurize the system? Is this incorrect?

Thanks

[Early_S_Man]

HGP,

Since at oil change time with a hot engine ... there is only a minute or so difference in the age of any contamination in crankcase and oil tank, there should be no difference in viscosity. My assumption is that the great velocity with which the eight quarts of oil leaves the tank is causing a perception that there is some difference, but I don't believe that a measurement with a paint viscosity cup would show any difference! The simple fact is that the oil in the crankcase doesn't have as much 'head pressure' due to the relatively thin layer across the distance of both cylinder banks and the surface area of the bottom of the crankcase. Less head pressure out the same size drain plug hole equals lower velocity!

[H.G.P.]

Originally posted by Early_S_Man
HGP,

Since at oil change time with a hot engine ... there is only a minute or so difference in the age of any contamination in crankcase and oil tank, there should be no difference in viscosity. My assumption is that the great velocity with which the eight quarts of oil leaves the tank is causing a perception that there is some difference, but I don't believe that a measurement with a paint viscosity cup would show any difference! The simple fact is that the oil in the crankcase doesn't have as much 'head pressure' due to the relatively thin layer across the distance of both cylinder banks and the surface area of the bottom of the crankcase. Less head pressure out the same size drain plug hole equals lower velocity!

Yes, I change when hot-warm, and the tank flow appears thin, "splashy". If it makes any difference, I also change the oil frequently.

I also run two fuel filters , one before the pump, and one before the carbs and Holley regulator. The filter before the carbs is G3802A.

I'll re-check the pressure tomorrow. The pressure on the cockpit guage is excellent upon acceleration in all gears also.