How much oak chips - Grenache

I have ~30L of Grenache must starting the fermentation process. I have been fermenting & maturing in inert containers (plastic and glass) and last time round I felt the wine lacked a bit of tannic complexity that I would like to introduce via oak.

So I picked up a bag of medium-toasted French oak chips. The instructions say to use 5-15 grams per litre, for 1-3 days during fermentation process. That's pretty broad - I was wondering if anybody had suggestions for how much to use in a light red like Grenache (similar to Pinot Noir I guess). I definitely don't want to over-oak the wine - don't want it to taste too woody. I am thinking of using 5g/L in a muslin bag over 3 days. Does this sound reasonable?

During fermentation, since it sounds like you're shooting for lighter oak and lower tannins, go on the lower end to be safe.
After the wine is done fermenting and is clearing, you can take your time to add oak to your taste, over time, with small additions and tasting. Once you've overdone it, you can't take it back, although it will subside with aging.
If the tannins are too light for your taste after fermenting, they can be added in incremental steps as well.

Be careful there. Lots of commercial Grenache out there with no oak or aged in a neutral barrel (again little to no oak).

Thanks guys. I will definitely err on the side of caution.
Do you think it might be wiser for me to only introduce oak once primary fermentation is done? If so, would that mean leaving the chips in contact with the wine for longer?

What is the source of your Grenache? Fresh grapes? A Kit, Concentrate?

Chips are the lowest form (quality) of Oak. I would ferment the wine without any oak and then see how it taste down the road and then add some higher quality of oak like beans, spiral, stave.

Chips being so thin are fully extracted in about 10 days max.

Just to expand on what others have said, I wrote the following article a couple of years back. This might help guide you when it comes to oak...

http://www.winemakingtalk.com/take-on-oak.html