Least drain back

Messages
109
Location
Leominster, MA
I have several vehicles that get stored for the winter now (Dec to April). I had very bad luck with early Mobile 1 (back in 80s) where in a solid lifter vehicles the drain back was so bad that after 6 months, I had bad camshaft wear. The vehicle sat for 2-4 weeks at a time, 2-3X for the 6 months period. Sounded like dry starts everytime after sitting. Recently other folks tell me that they seem see that with synthetics still. I did some searches in the forums and I see drain back comparisions (ad Hoc - ie. no test data) on differences between synthetics, but how about other dino products ? vs synthetics etc.. Is there any ASTM test for this ? And corrosion protection after some given time ? Looks like a great group here. Thanks Jerry
 

Patman

Staff member
Messages
22,012
Location
Guelph, Ontario
[Welcome!] Jerry! If you choose an oil with moly in it, whether it's dino or synthetic, it should offer better protection for those long storage periods, as the moly now provides a layer of protection, virtually eliminating dry starts. What kind of vehicle is this?
 

Jerry

Thread starter
Messages
109
Location
Leominster, MA
The original vehicle was a 2.6L D-50 Mitsu pickup in the 80's that didn't like sitting around w/ mobile 1 in the pan (and not much anywhere else). Will look around for high moly ... Thanks
 
Messages
18,449
Location
East of IGO
Jerry, the oil filter anti drainback valve is to keep the dirty oil "crud in the filter" from back washing to the pump and the oil sump. It does not in a sense keep oil or oil pressure any length of time in the engine.
 
Messages
8,937
Location
SC
quote:
Originally posted by Steve S: Jerry, the oil filter anti drainback valve is to keep the dirty oil "crud in the filter" from back washing to the pump and the oil sump. It does not in a sense keep oil or oil pressure any length of time in the engine.
This is incorrect. The anti-drainback valve is there precisely to keep some measure of oil "up" in the engine and to keep the filter full to prevent "dry starts."
 
Messages
6,388
Location
Washington St.
G What prevents the hot oil from gravitating down the upper oil passages, out the lower oil passages, out the crankshaft bearings, and into the sump? All this is taking place downstream from the filter. Adhesion/cohesion of the oil to the metal?...maybe to keep an oily surface, but not to keep the passages filled. The antidrainback valve should keep the filter full of oil...depending on the quality of the materials the valve is made of, it's design, and the quality of assembly of the filter. This is one of the reasons I'm leery of cheap filters...cheap materials (nitrile instead of silicone rubber) and slap-together assembly. Ken
 
Messages
874
Location
Pacific NW
There's little chance of the anti-drainback valves I've seen keeping anything "up" in an engine beyond the filter. As was mentioned, that's not the normal flow anyway and oil will drain to the pan leaving only puddles, troughs, and residue within the hour. Again, I'm speaking of the engines I've worked on. There are probably designs where this varies. I haven't noticed anyone speak of siphoning yet. In homebrew tests I found suction created by pump passage drain-down helped empty the filter beyond what I expected. If the anti-drainback valve keeps a horizontally-mounted filter half full overnight I consider it a win. David
 
Messages
39,805
Location
Pottstown, PA
This is something that always bothered me about the anti drain back valve feature...... I can't imagine oil managing to find a way back to the pan through the oil pump. That is, the tolerances are too tight. The oil pump is a positive displacemnet pump with only a spring/ball to relieve any excess pressure. My reasoning is that if oil can "leak" through the oil pump when still ..would not oil "leak" somewhere under pressure (though the same loose tolerances allowing "non" positive displacement)? Now my dual filters are mounted on the fender of my TJ and appear to syphon "forward". I even put an industrial check valve with a Vicon ball on it to prevent the forward flow ..it lasted only a short time and I ended up remarking my dip stick to gauge my oil level (9.5 qts.). Help me out with this [Confused]
 
Messages
39,805
Location
Pottstown, PA
quote:
quote:Originally posted by Steve S: I am correct on what an antidrain back valve is for,honest on this one, please do not be upset at this.No, you're not correct. And I'm not upset. [Big Grin]
G-Man ...errr I sorta agree with Steve ...and for a couple of reasons. There are a variety of oil filters that do not remain filled when mounted ..they forward drain. How does this feature help them prevent "dry starts"? That is, it may be a "value added" feature on a particular engine ...but is not a universal truth. I've often quietly chuckled when someone says, "it prevents dirty oil from returning to the pan". The oil in the filter is identical to the oil in the pan (pre media) ..the only difference is that the reverse flow could allow the particles to potentially be expelled from the media and travel with it. That is, the "prevents reverse oil flow" for the sake of preventing reverse oil flow alone ..just doesn't flush. I believe the design intent is as Steve S. describes.
 
Messages
874
Location
Pacific NW
quote:
Originally posted by Gary Allan: This is something that always bothered me about the anti drain back valve feature......
Gary, they are positive displacement but that doesn't account for the margins. Specs allow up to ~.5mm gaps among rotors and the body, depending on facet. Might not cause an intolerable efficiency loss at n1000rpm but it will allow draining. The pump I tested was a used 4.0L Jeep pump which may have been tired. I should try this on my new 318 pump & see what happens... Just got a new camera so need excuses. (not really [Smile] )
 
Messages
8,937
Location
SC
quote:
Originally posted by Gary Allan: [QUOTE]G-Man ...errr I sorta agree with Steve ...and for a couple of reasons.
The stated purpose by the oil filter manufacturers for the anti-drainback valve is to prevent the evacuation of the filter when the engine is shut down thereby avoiding "dry starts" where everything upstream of the filter is starved for oil in the time it would take to refill the filter upon start up. To the extent the valve does keep oil in the filter, it will also keep SOME oil "up" in the engine, though I admit it won't be much—and it certainly won't maintain any sort of "oil pressure" upstream of the filter. An anti-drain back valve is probably never 100% effective, and the longer a car sits, the more oil will likely leak by it and into the pan. From what I gather, silcone valves are more efficient than the nitrile ones, especially for long drain intervals.
 
Messages
18,449
Location
East of IGO
G-Man II ,I worked 4 years as a fleet mechanic and 16+ years at a forklift dealership as a road mechanic. The accounts we serviced may have had forklifts,backhoes ,cars ,trucks,semis,boom trucks,etc,after sitting ,depending upon time and of course filter position the filters would be dry. Unlike the automotive trade, the commercial equipment manufacturers tend to promote length of life. They put out lots of info.I am correct on what an antidrain back valve is for,honest on this one, please do not be upset at this .Also the mitisubishi 2.6 has a trough under the camshaft that holds oil, so the camshaft should be oiled, but the rest of the oil in the engine will have drained back over time.
 
Messages
8,937
Location
SC
quote:
Originally posted by Steve S: I am correct on what an antidrain back valve is for,honest on this one, please do not be upset at this.
No, you're not correct. And I'm not upset. [Big Grin]
 
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