Use of mineral oil in grey water tank?

[AktivCanuck]

We have a Hymer Aktiv Class B camper van. One of the annual maintenance items the manual mentions is to add mineral oil to the grey water tank, but it doesn't say what type nor the purpose of doing so (lubricating valves?).

Having searched extensively online, I can see that there are numerous types of mineral oil; some clearly not suitable for RV use while others could be. My dealership where I get maintenance done has never heard of using mineral oil. They recommend putting the same chemical in the grey water tank that goes in the black water tank. Unfortunately, Hymer went out of business so I can't ask them what they intended to be done.

So my two questions are:

1) Does anybody put mineral oil in the grey water tank, and if so, what type and why?

2) What type of maintenance do you do with your grey water tank, and how often? Chemicals, flushing, other?

Thanks

[inthepines]

Originally Posted by AktivCanuck

We have a Hymer Aktiv Class B camper van. One of the annual maintenance items the manual mentions is to add mineral oil to the grey water tank, but it doesn't say what type nor the purpose of doing so (lubricating valves?).

Having searched extensively online, I can see that there are numerous types of mineral oil; some clearly not suitable for RV use while others could be. My dealership where I get maintenance done has never heard of using mineral oil. They recommend putting the same chemical in the grey water tank that goes in the black water tank. Unfortunately, Hymer went out of business so I can't ask them what they intended to be done.

So my two questions are:

1) Does anybody put mineral oil in the grey water tank, and if so, what type and why?

2) What type of maintenance do you do with your grey water tank, and how often? Chemicals, flushing, other?

Thanks

first I heard of it, I just use valve lube (both tanks) I also use a seal conditioner for the toilet seal. Although I don't use my tanks either but I'd like to think it's keeping it maintained if I ever choose to do so.

[pddgm]

Never heard of putting it in the tanks, but have been told to put it in p traps just a few drops and it will keep the water from evaporating over long storage or being away from home. I bought some from Walmart pharmacy and used it in our house drains and toilet, drains still had water in them when we got home after being gone all winter..

[fcbbob15]

Yup putting it in traps to keep them from drying out. But never in an RV but don't see that it would hurt. Needs to food grade and defiantly not Mineral Spirits.

[AktivCanuck]

Thanks for all the replies.

What about flushing the grey water tank? How often do folks drain it and then run water into it and drain it again?

[inthepines]

Originally Posted by AktivCanuck

Thanks for all the replies.

What about flushing the grey water tank? How often do folks drain it and then run water into it and drain it again?

I don't see any real reason to flush a grey tank unless you're dumping food down the sink, which I hope no one does.

[LETMGROW]

Originally Posted by AktivCanuck

Thanks for all the replies.

What about flushing the grey water tank? How often do folks drain it and then run water into it and drain it again?

Every time I'm on a full hook up site and preparing to leave.
Black tank gets the same treatment.
Both tanks get a couple three or more gallons of water for storage along with a shot of laundry detergent and a scoop of "Happy Camper" tank treatment.
Is it overkill? Maybe but I don't have tank problems or odors coming from the tanks.
We never put food particles down the sink drains. It goes from the dish pan to the toilet and gets flushed away.

[1JetDoc]

Originally Posted by inthepines

I don't see any real reason to flush a grey tank unless you're dumping food down the sink, which I hope no one does.

If you wash dishes in your sink, you're going to end up with food particles in your grey tank. Also, toothpaste residue from the bathroom sink and soap scum from the shower.

We've heard it helps to pour a bit of Dawn dishwashing liquid down the drains and then fill both tanks with fresh water and go for a drive before dumping the tanks at the end of the season.

If your RV is exposed to cold weather in winter months, it also helps to dump some RV antifreeze in each waste tank

[MrMark52]

Food grade mineral oil? Why? It’s in the gray or black tank and nothing in those tanks should be conveyed for human consumption.

Mineral oil in the drains to prevent evaporation is a reasonable idea, as long as you put enough to provide a decent layer of oil, say 1/8” or so. For most drains, that would be a 1/4 cup or so.

Dawn detergent in the gray or black points acts as a grease and oil cutter (remember the oil spill commercials where Dawn detergent is used to clean the little ducky’s feathers?).

Combining the Dawn detergent with Borax helps to soften the water which makes it more aggressive toward breaking down solids.

Adding 1/4-1/2 cup of Dawn detergent and Borax to 3-5 gallons of fresh water to your emptied gray and black tanks and then driving provides the agitation needed for the above cleansers to work. Adding the same amount of orange citrus will help combat odors.

If possible, draining and refilling the tanks after agitation thru driving would be more beneficial.

Following the above practice should reduce your chances of poo-pyramid buildup and tank sensor fowling. And if your tanks are already fowled, then following the above practice will bring your tanks back to life.

[inthepines]

Originally Posted by 1JetDoc

If you wash dishes in your sink, you're going to end up with food particles in your grey tank. Also, toothpaste residue from the bathroom sink and soap scum from the shower.

We've heard it helps to pour a bit of Dawn dishwashing liquid down the drains and then fill both tanks with fresh water and go for a drive before dumping the tanks at the end of the season.

If your RV is exposed to cold weather in winter months, it also helps to dump some RV antifreeze in each waste tank

seems like a waste of money/time/water to me. I wash with dawn, I preclean the plates and soap scum toothpaste seems a non issue to me.

I guess it depends on how someone cleans/does things before cleaning.

If you rinse greasy plates off into the sink, yea you probably want to clean your tank well.

[MrMark52]

I will add -

I’m not real sure what more the “seals” will be lubricated using mineral oil over the body oils, oils, and greases already in the tanks from normal use.

On our coach, I thought I was going to have to remove the dump valves as the gray tank stem was hard as heck to pull and push. Then a few push/pulls later, easy-peasy. Then hard as heck again.
Then the black tank did similar.

I experimented - got out my trusty can of silicone a few shots on the valve stems, worked them in and out (empty tanks but still connected to a waste dump) - and I darn near crashed my head into the side of the coach as the t-handle easily slid closed.

That was almost a year ago and a dozen or so uses since. As easy to open and close today as the day I hit ‘em with silicone.

So, mineral oil in the tanks might minimize the beginning formation of a poo-pyramid in those instances when poo is dropped from the toilet onto the dry surface of the tank (a gross concept but not other tasteful way I can think to describe it . You know, the icky sticky factor or poo.).
But then how much mineral oil does it take to keep the tank surfaces “wet” with oil?
Just keep some water in the tanks - add some Dawn and Borax as described previously.

[Jay D.]

a while back there was several posts about putting a cup or two of corn oil in the black tank. it was said to make things slide out better and lube the valves. i tried it and didn't notice any difference.
Jay D.

[Ray,IN]

Originally Posted by Jay D.

a while back there was several posts about putting a cup or two of corn oil in the black tank. it was said to make things slide out better and lube the valves. i tried it and didn't notice any difference.
Jay D.

ALL oils are lighter than water and float on top of any water in the tank. Then oil sticks to the sides of the tank when draining-leaving a residue on sensors.
The only chemical I ever add to my holding tanks is lots water to keep solids covered. Guess it works, I haven't had any holding tank issues for over 40 years.

[Mudfrog]

Originally Posted by Ray,IN

ALL oils are lighter than water and float on top of any water in the tank. Then oil sticks to the sides of the tank when draining-leaving a residue on sensors.
The only chemical I ever add to my holding tanks is lots water to keep solids covered. Guess it works, I haven't had any holding tank issues for over 40 years.

This is the way I see it as well. I'm a bit over 40 years with RVing and usually only use water in the tanks. Not one issue in all these years. I would never purposely add any kind of oil to a holding tank. Holding tanks are simple devices and in my opinion, don't require all this "over thinking" that we see so often on here at times.

Edited to add: Went back and reread the OP. Don't think I've ever tried to do any kind of maintenance on a gray tank. Have never flushed the gray or black water tanks on any of our rigs. I do make sure to only dump the black when it has lots of water in it, over half full, to get that good "woosh" during the dump. Usually only water but I do sometimes use the blue stuff in the black tank to help keep the smell down when actually dumping. I don't believe it does anything else for the tank.