Originally Posted By: Dave9
Lithium spray can grease. You want the propellant carrier to get it down into tight clearances, then evaporate away leaving a thick film.
If it's grimy you might consider liberally flushing old grime and grease out with gasoline first, putting a very large amount of spray grease on the hinge, working it into the hinge by moving the door while it's still *wet*, and finally cleaning away excess from surrounding areas.
If it's a very old vehicle and the grease has hardened, it may need a few applications of gasoline to loosen up the old grease first. WD-40 and other spray oils can also loosen up old grease, but is more expensive, does no better at it, and is not meant to be a final lubricant so it doesn't save you from doing the next step of using the spray lithium grease.
You "can" just put a couple drops of oil on it. If there is existing grease that can work, but will not lubricate as well or last as long and tends to run out more and make a mess later, while the spray lithium grease is near full viscosity within a minute or so and shouldn't run out after initial cleanup, unless there was excess gasoline or oil left behind from a cleaning step mentioned above.
If you don't have a lot of vehicles to do, I might hesitate to buy a can of spray grease just for this purpose. You can achieve a similar effect by just mixing gasoline with tube lithium grease to thin it, dabbing it into the hinge with a toothpick or whatever liberally, working it into the hinge as mentioned above, and wiping off excess. It is not a high stress application and merely needs to get the grease in, not a special grease per se, but odds are the original was lithium so do use a compatible grease. If it has a plastic bushing it was more likely silicone instead.
Gasoline to clean and/or carry grease in seems sensible.
The thing is, what are we trying to accomplish? Im assuming that most car doors do not have bearings. Just a pin and some knuckles. Is that true?
Are we trying to get lubricant into/onto the shaft in the hinge? Are we trying to ensure that the knuckles are sliding well on each other? Or are we trying to get lube in there so that the knuckles slide properly about the pin?
Its not entirely clear to me how the car hinge is set up typically; and therefore what the end strategy is...
But I can watch penetro go into a hinge far better than most anything else, especially grease...