What lubes can I put through the air transfer port

Modern guns with synthetic seals need very little oil and a couple of drops of chamber lube or silicone oil every two or three thousand rounds is usually plenty.

I have gone far longer between oiling sessions with my Diana 54.

The old leather seals on the other hand require oiling every few hundred shots. Once again apply the oil sparingly.

The guns will usually, squeak or make a honking sound, when you cock them, or loose velocity, when they need oil.

What silicone oil do I use? What brand?

RWS and Crosman both market some silicone chamber lube but I only had some 3-in-one silicone oil. So, that is what I used on my Diana 45. It seems to quiet down the honking and squealing of the gun when being cocked. It is silent and smooth when cocking now. It did detonate for two shots before it returned to normal firing after the two drops of oil though. Probly should have left it sit overnight for the carrier to evaporate a bit more. I have never checked it with the chrony to see the results. 

Before that I used the Beeman Penta-dry, a couple of times, although I never trusted the stuff for some reason.

Interesting ! The last time I lubed the chamber (RWS chamber oil) on my FWB 124D with one drop it didn't even diesel once ! I thought that I didn't squeeze the bottle hard enough. After about 4 shots I noticed a very faint amount of smoke in the barrel after firing. It produced no smoke prior to the oiling. This was the first time I oiled the chamber and didn't get a first shot "crack" ! One thing I do is refrain from firing the rifle right after lubing. I let the rifle lay in different positions and periodically cock and uncock the rifle. The beauty of a gun without the anti-bear trap safety feature. I then let the gun sit overnight to allow some of the lube to evaporate off. Works for me !


 
I'm in the camp of no oil in the transfer port, silicone or otherwise. Especially in a Hw90. You'll be lucky if it doesn't burn through the factory seal without adding oil to it. Weihrauch has been over lubricating their guns the last couple of years. The Hw90 is a very high pressure gun that burns through factory seals if it just lightly overcharged when lubed correctly. It happened to my Rx1. 

In my early days of playing with springers I used the RWS silicone oil in a Hw30. After adding just three drops it clocked over 900fps and blew out the seal. So it will detonate if you use too much. I still have the bottle and you can have it for the cost of postage if you want.

Silicone oil has no place in an airgun. Even a leather sealed gun has to have better options because silicone is absolutely a terrible metal lubricant that contaminates and degrades the rest of the proper lubricants. There's always a thin layer of grease throughout the compression stroke in the best sealing airguns. Silicone oil will only wash that away. 

Do what you want, but you're a thousand times more likely to do more harm than good. I never lube my guns through the port (or cocking slot) and I get tens of thousands of shots on my guns between seals.

" After adding just three drops it clocked over 900fps and blew out the seal. "

Like I said, some people over lube their airguns. As you just indicated.

Yep I over lubricated it. By one drop of RWS silicone oil in a low powered gun. It blew out the seal and the spring broke shortly there after. Coincidence? My point is that it's easily overdone and the consequences are much greater than the benefits. I don't see a need to lube synthetic sealed airguns. I can't comment about leather sealed guns other than silicone oils wash out other lubricants and your once again dancing with the devil by using them. I'm sure there was something other than silicone oil used decades ago when leather seals were the norm.




 
It's all a balance between running the rifle bone dry of lube or blowing it up like a diesel engine. I don't think a drop of silicone chamber every 500-1000 shots will break springs and fry seals on every airgun out there ! If it were the case airgun manufacturers wouldn't be recommending sparingly use of chamber lube. Your results are your story. Stuff happens! 
 
It's all a balance between running the rifle bone dry of lube or blowing it up like a diesel engine. I don't think a drop of silicone chamber every 500-1000 shots will break springs and fry seals on every airgun out there ! If it were the case airgun manufacturers wouldn't be recommending sparingly use of chamber lube. Your results are your story. Stuff happens!

Yah, but they don't recommend it. RWS does, but Weihrauch and Air Arms and basically all the rest specifically recommended against it.

And only RWS sells their own branded overpriced little bottles of "chamber lube" yet all the brands use the same type of piston seal. Coincidence or good marketing? 
 
It's all a balance between running the rifle bone dry of lube or blowing it up like a diesel engine. I don't think a drop of silicone chamber every 500-1000 shots will break springs and fry seals on every airgun out there ! If it were the case airgun manufacturers wouldn't be recommending sparingly use of chamber lube. Your results are your story. Stuff happens!

Yah, but they don't recommend it. RWS does, but Weihrauch and Air Arms and basically all the rest specifically recommended against it.

And only RWS sells their own branded overpriced little bottles of "chamber lube" yet all the brands use the same type of piston seal. Coincidence or good marketing?

Dont forget that Beeman sold airguns which came with a maintenance guide called Pellets and Pistons. That guide came with Weihrauch, Webley, Feinwerkbau, and other rifles they sold. Chamber lube was sold and recommended. To each their own ! 
 
It's all a balance between running the rifle bone dry of lube or blowing it up like a diesel engine. I don't think a drop of silicone chamber every 500-1000 shots will break springs and fry seals on every airgun out there ! If it were the case airgun manufacturers wouldn't be recommending sparingly use of chamber lube. Your results are your story. Stuff happens!

Yah, but they don't recommend it. RWS does, but Weihrauch and Air Arms and basically all the rest specifically recommended against it.

And only RWS sells their own branded overpriced little bottles of "chamber lube" yet all the brands use the same type of piston seal. Coincidence or good marketing?

Dont forget that Beeman sold airguns which came with a maintenance guide called Pellets and Pistons. That guide came with Weihrauch, Webley, Feinwerkbau, and other rifles they sold. Chamber lube was sold and recommended. To each their own !

Beeman didn't make rifles, keep that in mind. He was nothing more than a con-man......errr......I mean "distributor".

Weihrauch, Webley and Feinwerkbau never sold a "chamber lube". Isn't that interesting?

It was only recommended by the guy who was trying to sell you the little bottle. 

Coincidence? 
 
He also sold other mouse milk formulas to go in the chamber. Not recommended by anybody anymore. Anyone still putting Beeman Pena Dry in the chamber lately?

I'm not convinced chamber oil is so harmful if used judiciously in guns lower than 12 ft lb. Can definitely be violent in magnums.

The OP inquired about his HW90. I can tell you from the start Theoben recommended you put NOTHING in their chambers.
 
It's all a balance between running the rifle bone dry of lube or blowing it up like a diesel engine. I don't think a drop of silicone chamber every 500-1000 shots will break springs and fry seals on every airgun out there ! If it were the case airgun manufacturers wouldn't be recommending sparingly use of chamber lube. Your results are your story. Stuff happens!

Yah, but they don't recommend it. RWS does, but Weihrauch and Air Arms and basically all the rest specifically recommended against it.

And only RWS sells their own branded overpriced little bottles of "chamber lube" yet all the brands use the same type of piston seal. Coincidence or good marketing?

Dont forget that Beeman sold airguns which came with a maintenance guide called Pellets and Pistons. That guide came with Weihrauch, Webley, Feinwerkbau, and other rifles they sold. Chamber lube was sold and recommended. To each their own !

Yes. One drop is good. I do agree. It wouldn’t hurt and more than not help the rifle. But, again a Weihrauch doesn’t even need it…it’s only if I start hearing a slight honk that I’ll put one drop in. Otherwise, they design it to last thousands before a reseal.
 
It's all a balance between running the rifle bone dry of lube or blowing it up like a diesel engine. I don't think a drop of silicone chamber every 500-1000 shots will break springs and fry seals on every airgun out there ! If it were the case airgun manufacturers wouldn't be recommending sparingly use of chamber lube. Your results are your story. Stuff happens!

Yah, but they don't recommend it. RWS does, but Weihrauch and Air Arms and basically all the rest specifically recommended against it.

And only RWS sells their own branded overpriced little bottles of "chamber lube" yet all the brands use the same type of piston seal. Coincidence or good marketing?

I’ll come back to this thread in a years time and let you know how it goes for me. This, of course, will be my own experience.
 
It's all a balance between running the rifle bone dry of lube or blowing it up like a diesel engine. I don't think a drop of silicone chamber every 500-1000 shots will break springs and fry seals on every airgun out there ! If it were the case airgun manufacturers wouldn't be recommending sparingly use of chamber lube. Your results are your story. Stuff happens!

Yah, but they don't recommend it. RWS does, but Weihrauch and Air Arms and basically all the rest specifically recommended against it.

And only RWS sells their own branded overpriced little bottles of "chamber lube" yet all the brands use the same type of piston seal. Coincidence or good marketing?

Dont forget that Beeman sold airguns which came with a maintenance guide called Pellets and Pistons. That guide came with Weihrauch, Webley, Feinwerkbau, and other rifles they sold. Chamber lube was sold and recommended. To each their own !

Beeman didn't make rifles, keep that in mind. He was nothing more than a con-man......errr......I mean "distributor".

Weihrauch, Webley and Feinwerkbau never sold a "chamber lube". Isn't that interesting?

It was only recommended by the guy who was trying to sell you the little bottle. 

Coincidence?

I know Beeman didn't make the airguns with their name stamped on them ! They didn't make the chamber oil they sold either and although I'm not certain I'd take a guess and say it was made in Germany. I gave chronological data that 1 drop every couple of tins will has kept my 124 shooting at its peak. Long after the drop was added. And without any harsh dieseling the last time I did it ! To each their own.
 
He also sold other mouse milk formulas to go in the chamber. Not recommended by anybody anymore. Anyone still putting Beeman Pena Dry in the chamber lately?

I'm not convinced chamber oil is so harmful if used judiciously in guns lower than 12 ft lb. Can definitely be violent in magnums.

The OP inquired about his HW90. I can tell you from the start Theoben recommended you put NOTHING in their chambers.

True ! None of the gas-spring airguns recommended putting anything in the chamber.