You can use WD-40 on all moving parts.etc..upper and lower arms,c-hubs,drive cups were the dogbones sit,as for how often,you should inspect and clean your truck after every run,check all the screw makeing sure none are ready to fall out and such,check your wheel nust every time you come in for fuel.As for changing your shock oil...now stock shocks come with i believe 20-25,000 weight oil in them..if you want stiffer response from your shock..use a little thicker oil in them...to do this..simply drain out the oil..compress the shock all the way in..then add the oil...filll the shock right full...then slowly pull out the shock..work it in and out till you get rid of all the air bubbles in the oil(trapped air)when you are finished top off the oil so it makes a small bubble over the end of the shock..in other words..right full...with the shock compressed fully inside the chamber add your cap and your shock will now have a slightly stiffer action to it now...repeat for all 8.If done right when screwing on your cap the shock should push out slightly when tight.
Your air filter is a must clean item...clean it after every run,if this is dirty it will lead to a bunch of running problems..etc..over heating,eating glow plugs..your engine needs air..and if you restric it to much(dirty filter) it will give you the signs of a lean running engine and you will be chasing a tune all day,not to mention do damage to your engine also.
After your done running you should go over the truck totally till you get used to what the problem areas are,check everything...plus remove your plug and add some after run oil then turn the motor over to insure a good coating.
Glow plugs should be checked every time also...and changed if your coil is dis coloured in any way like black,grey..or even broken..change it out.also.rememebr to dump out your old fuel when your finished for the day also the fuel evaporates and leaves a oily residue inside your engine.
-joe
