I agree with the OP there is a lot of older and/or conflicting info on the forum about batteries. The O'Reilly Super Start vented and AGM may have a part # of MIATA not 35-72. However, I can't find any info on a manufacturer or a spec sheet for the O'Reilly Super Start. O'Reilly may also have an AGM based on this link (). I'm not sure about O'Reilly batteries as they don't have a spec sheet for their Super Start 35-72 but I think it's a liquid not AGM battery. Napa also says ((P_RecType%3aA))that their BAT 7581R is wet, which I assume is liquid? No spec sheet for NAPA but I think their battery is made by Exide and Exide says that their Miata battery is wet (). Marathon calls theirs a 'Sealed Lead Acid Battery.' East Penn calls theirs a 'Valve Regulated Lead Acid Battery, Non-Spillable' but the spec sheet () also says 'Gel: Absorbed Electrolyte Sealed Valve-Regulated Non-Spillable Battery.' The photos of both the Deka and Marathon seem to be the same battery (also the Westco).īe careful with the Autozone Duralast Gold that they call the 8AMU1R or U1RT-DLG, the Autozone spec sheet () says that it is a wet, lead acid battery. You also need to cut the Miata vent tubes to fit the round vent on these batteries. (I haven't decided on one yet but I'm leaning toward one of these). Some companies say 'no maintenance' but if you search and find the fine print you'll also see something like Interstate's ''Maintenance: Removable caps allow water to be added, if needed, extending battery life.'ĭeka (manufactured by East Penn Mfg.) 8AMU1R or Marathon (from Battery Mart and also mfg'd by East Penn I believe) MAR-8AM-U1R seem to be AGM batteries. The caps can be pried up with a sharp tool (I did on my Mazda battery and found one cell low on acid). Even though some of the recessed caps are covered by a label they are liquid not agm batteries. Some of the batteries that you might think are sealed (like the Autozone Duralast and the new Miata battery by Mazda) are not sealed. I've been looking for a battery for a couple of months for my 96 and here is what I've been able to put together from various websites (summarized at the bottom and with apologies to Yogi): See page 2 of the Optima spec document here. With all the electrical items in the trunk capable of producing a spark (directionals, brake lights etc) I don't want even the slightest possibility of flammable gasses in my trunk. Wrong there are safety valves on the Optima D51R that will open if the battery is overcharged thereby discharging flammable gasses into the trunk. This IMHO is the best AGM battery for the NA. The vents are no longer needed as this type of AGM (spiral cell) does not have vents. My personal choice of a current proper replacement battery is the Optima Yellow Top D51R.

I wrote the Miata battery article (and follow up) that appears in the Garage section.

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