I very seriously doubt that it is a gel Cell.
Optima are NOT gel cells (though they false advertise they are)
What Optimas are is AGM..
Your starting battery is likely either Maintenance Free wet cell (Valve Regulated Lead Acid) or AGM (Also Valve Regulated Lead Acid, however with the addition of Starved Electrolytic)
There is a lot of things about two (GEL and AGM) that are alike, they both are VLRA, they both can be mounted in odd configurations (On end, side, angle or puside down) They are both able to co-exist with some electronics
But where as AGM's are one of the best, GEL is about the worst for RV or ENgine use. You need to be very very very careful charging a GEL, AGM's are able to accept a much faster charge.
GEL's are very hard to find in Automotive/RV sizes... Last device I had that used GEL was purachased in about 1970. Last Gell cell I purchased about 8 years later.