Itinerant Air-Cooled

Checked oil prior to leaving work and was slightly under full mark. Drove home 18 miles then park. Go to work that night and park in the same spot. 18 miles to work. Check oil prior to leaving and now it shows right at the low mark. Drive to local flaps near home 17 miles I park and go inside for oil. Come back out and check oil and it's at the full mark. What gives? I've noticed this for quite sometime now. Any thoughts?

I know that slight changes in the vehicle axis while parked can vary the readings. I also know the most accurate oil check is just prior to cold start on level surface. I also see differences in the reading based on the insertion of the oil dipstick iteslf. Such as handle up vs handle or handle left vs handle right. I generally face the handle to the right (towards oil spout). I feel it's the most accurate given it keeps the marks on the stick relatively level to the oil in the crankcase. As opposed to facing down (in the oil) or up away from oil surface. Perhaps it has to do with the stick going in at an angle as opposed to straight down?

This is a type 4 engine. Hasn't been molested and everything is in working order. I've been with the bus since it was purchased in 72' new. Would really like to get to the bottom of this.

Using Mobil 1 Extended Performance filter and Valvoline ZR1 10-30.

I've confirmed there is no fuel in oil. I rebuilt the fuel pump and rebuilt the carbs. (40mm webers). Parking spot at work is very level. Noticed this for sometime now even prior to rebuilding the fuel pump & carbs.

Switch to a Mann oil filter and Brad Penn oil. I think you have a leaking oil filter bleed down valve that gets stuck sometimes. That oil (IIRC)does have enough Zinc nowdays for the type 4 engine.

Oil will "wick" up the dipstick if it has sat awhile. Make sure you wipe the stick with a rag, reinsert it and then check the level. Geoff's suggestion of a leaky filter anti-backflow valve is valid as well.

Yes switch oils that modern oil offers no protection for the flat tappet cam....Use Brad Penn or Shell Rotella T available at any LAPS.

Bleyseng wrote:Switch to a Mann oil filter and Brad Penn oil. I think you have a leaking oil filter bleed down valve that gets stuck sometimes. That oil (IIRC)does have enough Zinc nowdays for the type 4 engine.

I was under the impression based on some testing and analysis of oil filters that the Mobil 1 filters were very good. This issue was also present when I used either a Mahle or Mann filter as well. How would the drain back valve cause it if it were sticking given the filters position? I always wipe first and dip prior to actual read.

These are only $20 at Amazon. Might be handy in troubleshooting if there is a real problem or just a lot of slight inclines where you check your oil at.
Also - more gauges = more fun.

72Hardtop wrote:

Bleyseng wrote:Switch to a Mann oil filter

How would the drain back valve cause it if it were sticking given the filters position?

NAPA #1521 filters have very good anti-drainback.
What I think you are getting is an oil level rise in the sump if the galleries are all draining and even a little cooler/filter syphoning back into the sump. Other times, the oil is held in the cooler/filter/galleries like a finger over the top of a full straw, and it would read "unusually low".
ColinICheckItHot

Amskeptic wrote:

72Hardtop wrote:

Bleyseng wrote:Switch to a Mann oil filter

How would the drain back valve cause it if it were sticking given the filters position?

NAPA #1521 filters have very good anti-drainback.
What I think you are getting is an oil level rise in the sump if the galleries are all draining and even a little cooler/filter syphoning back into the sump. Other times, the oil is held in the cooler/filter/galleries like a finger over the top of a full straw, and it would read "unusually low".
ColinICheckItHot

Well I added a 1/4 qt the morning it showed low. Drove to work that night parked in the same spot and checked the oil prior to leaving for home. Whatta you know...it now showed approx. 1/4qt. over full mark.

Regarding your explanation Colin...What would cause this? (Oil filter, relief valve etc...) Any good remedy?

72Hardtop wrote:
Regarding your explanation Colin...What would cause this? (Oil filter, relief valve etc...) Any good remedy?

LEAKING ANTI-DRAINBACK
What I think you are getting is an oil level rise in the sump if the galleries are all draining and even a little cooler/filter syphoning back into the sump.
READS "HIGH"

HOLDING ANTI-DRAINBACK
Other times, the oil is held in the cooler/filter/galleries like a finger over the top of a full straw, and it would read "unusually low".
READS "LOW"

Don't worry about it, really. Check your oil hot and after a few minute sit, and you will have a decent opportunity to keep the oil reasonably level reasonably consistently.
The engine knows how to survive variations in oil level.
Colin

Amskeptic wrote:

72Hardtop wrote:
Regarding your explanation Colin...What would cause this? (Oil filter, relief valve etc...) Any good remedy?

LEAKING ANTI-DRAINBACK
What I think you are getting is an oil level rise in the sump if the galleries are all draining and even a little cooler/filter syphoning back into the sump.
READS "HIGH"

HOLDING ANTI-DRAINBACK
Other times, the oil is held in the cooler/filter/galleries like a finger over the top of a full straw, and it would read "unusually low".
READS "LOW"

Don't worry about it, really. Check your oil hot and after a few minute sit, and you will have a decent opportunity to keep the oil reasonably level reasonably consistently.




Colin

Figure I gotta ask...

How is it that the oil can be held back after a run? Let me get this. A leaking drainback valve allows the oil to drain back to the sump for an accurate reading? Whereas a holding drainback valve won't?

72Hardtop wrote:

Amskeptic wrote:

72Hardtop wrote:
Regarding your explanation Colin...What would cause this? (Oil filter, relief valve etc...) Any good remedy?

LEAKING ANTI-DRAINBACK
What I think you are getting is an oil level rise in the sump if the galleries are all draining and even a little cooler/filter syphoning back into the sump.
READS "HIGH"

HOLDING ANTI-DRAINBACK
Other times, the oil is held in the cooler/filter/galleries like a finger over the top of a full straw, and it would read "unusually low".
READS "LOW"

Don't worry about it, really. Check your oil hot and after a few minute sit, and you will have a decent opportunity to keep the oil reasonably level reasonably consistently.




Colin

Figure I gotta ask...

How is it that the oil can be held back after a run? Let me get this. A leaking drainback valve allows the oil to drain back to the sump for an accurate reading? Whereas a holding drainback valve won't?

Dispense with "accurate" versus "inaccurate". Let's use the words "fooled you" and "didn't fool you".

If you just did an oil and filter change and put in by God the correct amount of oil! your reading will be high. Yes it will. Once you start the engine to fill the filter and galleries, it will "drop" to normal. Sort of.

So when do you get fooled? When the drainback valve leaks down, or when it holds?
Well, with a Type 4 engine, I like giving the camshaft every advantage, so I like it when it holds the oil in and "reads low" and I keep the oil level at the upper mark after a three minute wait on a hot engine. If it reads "high" tomorrow morning I don't care! Happy camshaft! The amount of this "discrepancy is no more than a pint anyway.

With a Type 1 engine, it does not have a rear seal at the crankshaft pulley, and it has a more marginal breather, so I keep the oil level full cold morning, but it does not seem to deviate like the Type 4 engine anyway.

Figured I'd post this here since it relates somewhat...

Anyone else notice variations in readings based on what direction the dipstick is inserted? IOW...dipstick handle say 9:00 versus 5:00. I'm seeing between 1/8th - 1/4qt difference roughly. So which position is more accurate. Bus is parked on level surface and always wiped before final reading.

Mine reads at 5:00 position roughly 1/8qt low. At 9:00 position it is just above the full mark an 1/8th.

Weird

Bahhh. Keep it above the bottom mark and worry less. The whole reason there are two marks on the dipstick are to compensate for natural variations in the indicated level. Don't add until it is below the bottom mark, don't add more than it takes to get to the middle. Unless there is evidence of major oil leakage or consumption, stop checking the oil so often, do it when you fill up/once a week and just enjoy the drive more!

Also, I too use Valvoline ZR-1, but 20w50. Was under the impression that it was formulated for flat-tappet cams and high temps.

God, if only you guys could see the abused engines I see day in and day out. Hippies that put 20,000 miles on 'em in a summer without poppin the decklid once, driving until the points completely fry and stick shut or it runs so low on oil the lifters quit. And a quick tune'n'change gets 'em down the road for another year. These are resilient beasts!

Mobil 1 filters are good, but their ADBVs suck. You usually have to blow into several of them (center hole) to find one that seals, new in box. In a filter with the threaded end mounted up, that is not a big concern, in my opinion.

Hippie wrote:Mobil 1 filters are good, but their ADBVs suck. You usually have to blow into several of them (center hole) to find one that seals, new in box.

Must make the customers and staff at the auto parts store wonder what kind of fetish your are indulging.....but I'm going to try it next time anyway.