Many don't bother with a gasket. I like a gasket just for the cushioning it provides when closing the dome. Quiet instead of that awful "clacking" sound. Also, you probably burn more lump during the shut down process than you would if it were better sealed.

the original manual (50s-50s era) refers to the gasket's purpose as what @carolinaQ mentions, simply a cushion for when you shut the dome, avoiding slamming ceramic against ceramic.

my gut though is that this gasket is what makes the difference (aside from the ceramic of course, which is insulative) between this and kettle cookers, and what made the BGE essentially air tight

i doubt anyone purchased them originally for low-and-slow cooks (my mental picture of the 50s-60s is hamburgers and hot dogs and steaks), but maybe eventually when it was discovered how closely you could dial in the temps (and hold them), the gasket began to be seen as more important.

yes, you can cook without one.  those who do have said it is not a big deal that it is not airtight.

it's logical that if the ungasketed egg does maybe let in a little extra air, that you'd just habitually dial back the vents, and still be able to cook low.

whether the leak really allows air in during a cook (that'd be an odd draft that comes in, goes down, mixes with incoming air from the lower vent, and then goes up and out), i dunno.

BUT

 i was able once to use a gasketless egg for an extended weekend, along with a very dense long lasting charcoal, 'wicked good'. i had my own BGE at home, airtight with a rutland, but this was a vacation house i was renting.

i filled it as i always do, pretty much full (even though I am not going to use it all).  i cooked on it, and then shut down the egg (rain cap and lower vent shut) for the night.

when i went to use it the next day, most of the remaining charcoal had burnt out.

what the....? this simply doesn't happen in my own BGE

the egg's owner mentioned later that he only really uses as much lump as he needs for each cook.

so, it appears temp control is minimally affected (if at all).  but in my experience, having regularly used a gasketed egg daily and then immediately switching to a gasketless (at a vacation house), i noticed the difference.  and it was significant.

it took much longer to shut down, and most of my extra lump was used up.

YMMV

No, only really need as @Carolina Q said. 6+ years on a Large and a Mini without. When the other Large and Mini-Max go away I will not replace. 

Hans61 said:

I'd figure cracks in ceramic more likely to occur or inevitable ones would be accelerated if constantly closing the lid with no gasket 

Might not want to drop it w/o gasket. But I don't drop it anyway so that's no problem. 

It depends on the egg. There are some that the dome and base are perfectly made, and there is no gap. Some are uneven which lets air in, and when done cooking it takes longer for the fire to go out. I have cooked on eggs with no gaskets and low and slows are no problem. If someone lets the dome slam you will glad if you have a gasket.

Gasketless for 2+ years and it works fine.  Overnight long cooks,  shuts down with no problem and plenty of lump left over. 

The only issue I have is when I cook a low n slow is I need to put the probe wires out the top as then it causes a gap between the base and dome if the wires were in the  way.

I have been needing to replace mine for a few years, have the material, just too lazy to do it I guess.  But everything works fine, so not much incentive to rush out and do it.  I guess mine has enough gunk built up after all these years that it closes quietly too !!

JustineCaseyFeldown said:

the original manual (50s-50s era) refers to the gasket's purpose as what @carolinaQ mentions, simply a cushion for when you shut the dome, avoiding slamming ceramic against ceramic.

my gut though is that this gasket is what makes the difference (aside from the ceramic of course, which is insulative) between this and kettle cookers, and what made the BGE essentially air tight

i doubt anyone purchased them originally for low-and-slow cooks (my mental picture of the 50s-60s is hamburgers and hot dogs and steaks), but maybe eventually when it was discovered how closely you could dial in the temps (and hold them), the gasket began to be seen as more important.

yes, you can cook without one.  those who do have said it is not a big deal that it is not airtight.

it's logical that if the ungasketed egg does maybe let in a little extra air, that you'd just habitually dial back the vents, and still be able to cook low.

whether the leak really allows air in during a cook (that'd be an odd draft that comes in, goes down, mixes with incoming air from the lower vent, and then goes up and out), i dunno.

BUT

 i was able once to use a gasketless egg for an extended weekend, along with a very dense long lasting charcoal, 'wicked good'. i had my own BGE at home, airtight with a rutland, but this was a vacation house i was renting.

i filled it as i always do, pretty much full (even though I am not going to use it all).  i cooked on it, and then shut down the egg (rain cap and lower vent shut) for the night.

when i went to use it the next day, most of the remaining charcoal had burnt out.

what the....? this simply doesn't happen in my own BGE

the egg's owner mentioned later that he only really uses as much lump as he needs for each cook.

so, it appears temp control is minimally affected (if at all).  but in my experience, having regularly used a gasketed egg daily and then immediately switching to a gasketless (at a vacation house), i noticed the difference.  and it was significant.

it took much longer to shut down, and most of my extra lump was used up.

YMMV

I could be mistaken but my understanding is that BGE was launched in '74; though obviously kamado cookers greatly predate this,