I just thought I'd share my thoughts as to carrying "spare lube" in the pistol grip. I think it's a great idea, and when done with a SMALL container, allows you to have that available AND other essentials you may want (FCG parts, Allen keys, Etc).
My current favorite is:
http://www.amazon.com/Mini-Dropper-Bottles-Natural-Clear/dp/B00EZIPEVI/ref=sr_1_2?ie=UTF8&qid=1436862042&sr=8-2&keywords=3ml+dropper+bottle

which looks like THIS (my photo):


I've also used THIS:

http://www.amazon.com/SODIAL-Dropper-Bottle-Plastic-Liquid/dp/B00N71YC8A/ref=sr_1_1?s=beauty&ie=UTF8&qid=1436862531&sr=8-1&keywords=SODIAL%28R%29+10+Pcs+Empty+Eye+Dropper+Bottle+Plastic+Eye+Liquid+Screw+Cap+Lids+5ml&pebp=1436862541592&perid=0M08XGTWTE45V7JNTAQX

And it works very well (a little larger 5ml vs the above 3ml) and fits in the grip but leaves room for other stuff. Personally, I think 3ml is all you'll ever need (will do multiple "emergency" re lubes without hogging up too much grip space).
For size reference, this is what the 5ml (short bottle, as linked above) looks like compared to grip:


IMHO, 5ml is too much. It fits, but it's a waste of space, 3ml is the right size, as it's more than a few "uses", and leaves quite a bit of space for other stuff.

Also, the way I transfer I oils (I use Mobile 1 10w30) into these containers is:

http://www.amazon.com/G2Plus-Disposable-Graduated-Transfer-Pipettes/dp/B00SY3USA2/ref=sr_1_3?ie=UTF8&qid=1436863437&sr=8-3&keywords=5ml+transfer+pipette

And for the photos, the grip was a Magpul K2.

Hope this helps anyone wondering (or considering) how to keep some "emergency" re lube onboard in their grip and gives them some size references per bottle ml size (keep in mind my pics are a 3ml "tall" and a 5ml "short" bottle).

Thx for the comparison. I like the Visine 5ml bottle, the shape seems almost designed to fit inside the K2 grip and I still have enough room for spare batteries for my MFT nav light and a nickel (aka tactical screwdriver).
Tomac

I just keep the small sample packs of frog lube in my grip, or the small sample of machine gunners lube that you get from LaRue

This works pretty good.

Yes, those small packs would be great too! I just prefer the dropper bottles because I can put my choice in them, AND they are re useable (not to mention they seal back up after each use).
I like the other options (packs) though too! Thanks for sharing guys

If you've got $15 to burn or you don't want your lube bottle rattleing around Magpul makes a special bottle that is designed to be stored in the MIAD/MOE grips
https://www.magpul.com/products/miad%C2%AE-moe%C2%AE-lube-bottle-core

No offense, but I'll choose a 20c refillable eye dropper over a $15 Magpul bottle ANYDAY (they should be ashamed at their price)!

They priced themselves out of my market. I'd probably be willing to pay $7 for a core. But $15? Ridiculous.

The MIAD comes with the bottle, I just use it

Use grease and you don't need to worry about carrying extra oil.

I use lithium grease in ALL of my piston rifles, but for DI... no way. Carbon/unburnt poweder/grit will turn that into paste. Mobile 1 oil for my DI's.

That is absolutely not true.  It will look like paste, yes, but it will still be lube when oil has dripped out and burned off.  Pretty much all of the trainers these days who are running a couple thousand rounds in a couple of days in a course suggest grease.  I've gone roughly 3500 rounds in about a year with nothing but grease, and it never turned to "paste".

I do this too.

+1. I've used bearing grease on all of my guns (pistol/AR/AK/shotgun) that have been through high round count classes and never had lube issues.  It's cheap and it flat works. Even loaned some to classmates when their expensive magic oils burned off or dried up.

No.

I purchased a Miad grip with the oil core for $30 and then sold the Miad grip without the oil core on the EE for $25. It was one of my first transactions here. Made out pretty well if I don't say so myself. The oil core works as advertised and is handy for range trips.

 

I'm mainly using the LaRue Tactical free small sample bottle Machinegunners Lube or my Steyr AUG squarish oil bottle filled with SLiP 2000 EWL lube in my mostly Magpul MIAD or MOE grips.

I've got no problems with any rattles because I just wrap the bottle with bore patches and everything in a zip plastic bag.

Your vehicle has a dipstick and a lot of oil, right?
This has worked for many years of mountain biking, for me.
Not to be a dick, or anything.

I don't carry lube in my grip for regular use, it's for emergency use. In an emergency (as in, away from supplies) I am not about to rely on having a vehicle nearby for accessing lube off it's dipstick. If I had access to my vehicle, well then I'd most certainly have access to my main supplies (and I'm not about to go around bashing other people hoods open to lube my AR, just saying)

The spare cr123 batteries from my light are taped up with electrical tape with a set of foam earplugs and they keep my 3ml bottle from rattling around

LOVE the 3ml dropper bottle (as pictured in my OP). 3ml is the perfect "emergency" ration. It leaves plenty of room in the grip for other stuff, yet is enough for quite a few "touch up's".
I have both the 3ml and 5ml, and IMHO... the 3ml (harder to find) is the bees knees.

Thanks for the ideas OP. Some great stuff there.

I run the MIAD, but use my own 3ml bottle and have room for other stuff.  Just stuff a little tissue paper in and you stop any rattle.  3ml of Shell Rotella T6 5w40 synthetic.

Id say a spare bolt is the best option

im lookin at this in a shtf situation....  I would think that sticking a spare bolt or something would be better than oil...

just due to the fact of  wherever you may be there is some sort of mechanical device around      

lawnmower,chainsaw,cars,boats anything that uses oil.  just pull out a dipstick and lube up!  

and yes I know someones going to say it   but if your in a desert with no transportation or on an island  you have bigger problems then lube...

I hear you, but think of it this way: your odds of needing lube FAR surpass your chances of breaking a bolt. If you get crud in your rifle (or sand), or it gets REALLY dry for some reason (firing, dirt, etc), you're going to want to wipe it down and lube it. Id rather do that in hiding, then expose myself trying to steal lube from an automobile (which almost ALL have locked hoods) or find some other machinery to steal it from.
There is NO doubt... you are going to need lube eventually. You may not need a bolt (probably slim chance).
Just my .02

I like to keep a spare bolt/fp in the grip and oil in the compartment on my ACS stock. There's plenty of room for watch type batteries, spare gas rings, extractor etc in there as well....

The Magpul bottle is honestly too big.  I need to oil a rifle,  not a handful of bicycles.

I use a small eye drop bottle, like the sample size. (3 mL)

So do I.

1) Cut off 2" section of drinking straw
2) Put small amount of bearing grease onto palm and pack into straw
3) Pinch down end of straw with needle nose pliers leaving 1/16"
4) Melt 1/16" section of straw with lighter to seal both ends
5) Put in grip
6) Spend $20 on something actually useful

... Or just use a 3ml dropper bottle filled (and refillable) with Mobile 1, like the rest of us.

"Us" has needed to bum $0.10 worth of grease more than once during classes.