Silicone is bad for O2/AF sensors. Cats aren’t as affected, vaporized silicone leaves a film on the sensor element.
Fuel Injector O-Rings - Lube or No?
- Thread starter AJB0009
- Start date
How about using a dry spray lube. However if a high end oil or grease works well or buy the special grease from Mercedes. part # 001989425110
Here is product info from ROCAL. [we use some of their products for thread tapping and machine shop operations.]
High purity, extreme load dry film molybdenum disulphide spray designed for use where a wet lubricant cannot be tolerated.
DRY MOLY Spray is applied wet for great penetration. The quick drying aersol is touch dry within 2 – 3 minutes, leaving a dry protective film containing more than 70% molybdenum disulphide.
DRY MOLY Spray is an assembly lubricant for sliding surfaces such as plain bearings, pins, cams and slides intended to reduce friction and therefore increase life of moving parts.
The aerosol lubricant spray can also be used in conjunction with a wet film lubricant enhancing performance and extending life of components and assemblies.
Here is product info from ROCAL. [we use some of their products for thread tapping and machine shop operations.]
High purity, extreme load dry film molybdenum disulphide spray designed for use where a wet lubricant cannot be tolerated.
DRY MOLY Spray is applied wet for great penetration. The quick drying aersol is touch dry within 2 – 3 minutes, leaving a dry protective film containing more than 70% molybdenum disulphide.
DRY MOLY Spray is an assembly lubricant for sliding surfaces such as plain bearings, pins, cams and slides intended to reduce friction and therefore increase life of moving parts.
The aerosol lubricant spray can also be used in conjunction with a wet film lubricant enhancing performance and extending life of components and assemblies.
Injector o-rings do not require a long term lubricant such as molybdenum disulfide. Anyway how would you know the carrier is safe for the application?
Use what the FSM states and be done with it.
Use what the FSM states and be done with it.
No way I would use a grease on o-rings. Some greases can damage the o-rings. I would use a silicone or something compatible.
Once they’re installed, they don’t need lubrication, so the moly is pointless…
Once they’re installed, they don’t need lubrication, so the moly is pointless…
Astro wow! I am impressed with your response!! 
I was looking at some of the responses and was surprised what some use. Depending on what the o-ring is made of and most are rubber and anything petroleum based will dry and deteriorate them. I personally have used leather treatment when I install new fuel injection seals or anything rubber material on an engine or transmission . And I have used that going all the way back to when F/I were first used in production engines. But back way back then I used my sisters English Leather Horse saddle treatment 
because automotive leather treatments with no petroleum were just ridiculously expensive.
I was looking at some of the responses and was surprised what some use. Depending on what the o-ring is made of and most are rubber and anything petroleum based will dry and deteriorate them. I personally have used leather treatment when I install new fuel injection seals or anything rubber material on an engine or transmission . And I have used that going all the way back to when F/I were first used in production engines. But back way back then I used my sisters English Leather Horse saddle treatment because automotive leather treatments with no petroleum were just ridiculously expensive.
Injector rings and seals are mostly Viton for at least the last 15 years. WD40, Superlube, engine oil or Vaseline (transgel is similar) is harmless to Viton.
https://www.calpaclab.com/viton-chemical-compatibility-chart/
https://www.calpaclab.com/viton-chemical-compatibility-chart/
Why take the chance and post this without explaining that most fuel injectors boxed packaged don't always state what the O-ring material is. Many DIY follow these threads and don't you think it would be better for them to use something that will not damage any type of o-ring.
I wont get into that the use of some thing you suggest will arrack dirt and debris. HA!
Ok now we have yet another thing that you do because you been doing it for years and I do it because I have been doing it for year debate. LOL .
Even before Viton they used Buna-N (Nitrile) which was also resistant to fuel, oil, atf, grease and almost any other fluid found in automotive systems except brake fluid. Natural rubber has not been used in engines for well over 50 years. So no, there is no argument.
Heat is the main cause of damage to Buna-N, as far as atracting dirt and debris you must be joking, you dont lather the stuff on and once installed the rings/head seal sealing surfaces are captured anyway.
An interesting fact for you. The o rings they use have to be resistant to gasoline otherwise you would have many millions of vehicles running around setting fire to everything in sight so they cannot be natural rubber.
https://www.efunda.com/designstandards/oring/oring_chemical.cfm?SC=none&SM=Buna-N (Nitrile)
Heat is the main cause of damage to Buna-N, as far as atracting dirt and debris you must be joking, you dont lather the stuff on and once installed the rings/head seal sealing surfaces are captured anyway.
An interesting fact for you. The o rings they use have to be resistant to gasoline otherwise you would have many millions of vehicles running around setting fire to everything in sight so they cannot be natural rubber.
https://www.efunda.com/designstandards/oring/oring_chemical.cfm?SC=none&SM=Buna-N (Nitrile)
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What?
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I am making fun of the idiots that believe that Dot 3/4 sucks water out of the air becuz it "hygroscopic." Yes, those idiots believe it sucks water through steel, copper, sealed reservoirs, etc.
If you intend sarcasm, or irony, please use an emoji, or some indicator that you don’t mean to be taken literally.
ya ok we can agree to do things differently I don't agree to much with what your methods you have a fan base here so you are "theman". I may be a little more meticulous about my work and consider long term effects of any service. I won't say I don't stray from a Factory service procedure from time to time but generally speaking they are there for a reason. I also consider somebody might work on something in the future I serviced and would rather have him think somebody took the time and care to do the job right or better instead of cookie cut and speed through a job because of labor dollars to get more done in one day. Not saying you do but we know there are shops that do.
Again my point that you miss is the use of leather condition will never harm any automotive (that I am aware of) no matter what they are made from.
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Clearly stating your intent is a courtesy to the reader.
Deliberately provoking a reaction is trolling.
Which side are you on?
Deliberately provoking a reaction is trolling.
Which side are you on?
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RRG may have been originally designed for natural rubber, but it is also Ideal for various iterations of "synthetic" rubber. Ask any knowlegable brake mechanic and they will tell you they would never be without it for rebuilding master cylinders and wheel cylinders. Of course the same goes for any hydraulic system.
4WD
$50 site donor 2025
Ford service manual said clean motor oil.
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Yes even most factory service manual say to lubricate them with clean eng oil.
