1987 Mondial Battery

I suggest replacing your old battery a similar one (personally, I have new interstate as well). It worked fine for 8 yrs, and will be less expensive and potentially finicky than AGM.

 

Optionstan,

Agree with Thorn. And to answer your 2nd question...YES, you will have to remove the front passenge wheel to replace the battery. There is no room to do it from the top.

Bill P.

 

AGM batteries (in general) are not more finicky than a standard flooded cell battery. An AGM is a direct replacement for a flooded cell battery and (in general) will have a longer service life, never requires adding water, has lower self discharge rate, and can withstand the occasional deep discharge better than a flooded cell battery. Granted not all AGMs are superior, but the benefits are well known, such that Consumer Reports recommends them as a worthwhile upgrade, and their testing generally bears out their superiority.

In most of CR battery ratings, you will usually (but not in all cases) see the AGM variants in the top spots of most battery sizes. Here is CRs take:
"AGMs are built to better stand up to repeated draining and recharging cycles than standard batteries. They are becoming standard equipment in more cars because modern features such as fuel-saving stop-start systems, electronic safety and convenience features, and power outlets for mobile electronics all increase the demand for power.

But AGMs can cost 40 to 100 percent more than highly rated conventional batteries. Consider buying one if you sometimes don’t use your vehicle for long periods and the battery loses its charge. An AGM battery can better tolerate a deep discharge, and it is more likely to fully recover if it is accidentally drained."

 

They're also far more sensitive to overcharging, and vintage exotics aren't known for perfect-calibrated charging systems.

 

Do you have documentation to support that, or just your experience? I have never known (or read) that to be the case. I had a Optima red top in my 78 308GTS for many years, without issue. Rarely even used a battery tender on it....always started first try.

But a constantly overcharging situation is something that should not be ignored. That will boil the electrolyte out of a flooded cell battery and should be corrected either way, regardless of battery type.