The S55 in the F8x M3 and M4 leans on a pair of auxiliary radiators mounted low in the front corners of the car. They sit in the worst place on the vehicle, first in line for road debris, and low enough that their plastic end tanks crack after enough heat cycles. This Mishimoto unit replaces one factory auxiliary radiator with an aluminum core carrying 9% more volume and 32% more external tube area than stock, so it rejects more heat and recovers faster between hard runs. The single-row core is 1.6 inches thick with strutted tubes to resist the vibration and stone strikes that fatigue a low-mounted radiator, and aluminum TIG-welded end tanks replace the factory plastic ones. A removable powder-coated steel stone guard shields the exposed face. One radiator ships per box, and the bracket design fits either the driver-side or passenger-side auxiliary radiator location, so the same part number covers both positions, order accordingly for the position or positions you are replacing. It is a direct fit in the factory auxiliary radiator location with no cutting, fabricating or adapters, and it is backed by the Mishimoto Lifetime Warranty. 9% more core volume and 32% more external tube area than the factory auxiliary radiator Aluminum core with strutted tubes and TIG-welded aluminum end tanks, no plastic tanks to crack Removable powder-coated steel stone guard protects the exposed core face Single bracket design fits both the driver-side and passenger-side auxiliary radiator locations Single-row core, 1.6 in thick Direct fit in the factory auxiliary radiator location, no cutting, fabricating or adapters Box contains (1) auxiliary radiator, (1) stone guard, (2) mounting brackets, (3) O-rings, (8) M6 lock washers and (8) M6 button head bolts Mishimoto Lifetime Warranty
Specifications
| Type | Performance auxiliary radiator |
| Material | Aluminum |
| Construction | Strutted-tube aluminum core with TIG-welded aluminum end tanks |
| Core Rows | 1 |
| Core Thickness | 1.6 in |
| Sold As | Sold individually - one radiator per box, fits either side |
| Included | (1) auxiliary radiator, (1) powder coated steel stone guard, (2) powder coated steel mounting brackets, (3) O-rings, (8) M6 lock washers, (8) M6 button head bolts |
| Direct Fit | Yes - factory auxiliary radiator location, no modification |
| Part Number | MMRAD-F80-15A |
Documents: Installation Instructions (PDF)
This part fits:
| Year | Make | Model | Submodel |
|---|---|---|---|
| 2019-2021 | BMW | M2 | Competition |
| 2020-2021 | BMW | M2 | CS |
| 2015-2018 | BMW | M3 | Base |
| 2015-2020 | BMW | M4 | Base |
| 2018-2020 | BMW | M4 | CS |
| 2016 | BMW | M4 | GTS |
Shipping
- Orders placed before 3 PM EST typically ship the same business day. Larger items ship within 1 to 3 business days.
- Standard, expedited, and overnight options at checkout.
- Oversized items ship by freight and take longer.
- Special order items follow a lead time we confirm with you individually before the order is committed.
- Backordered items ship as soon as stock lands. Lead times are manufacturer estimates and can change. Contact us for current ETAs.
- Need to cancel? Email us right away. Cancellations are not guaranteed once an order is in process. In-stock orders cancel free before they ship; a 6% fee applies only to confirmed backorders and special orders.
- International orders: prices do not include VAT, duties, or import fees. Your country charges these at import and they are the buyer’s responsibility.
Returns
- 30 days from delivery to request and ship back a return on new, uninstalled items in original packaging with all hardware.
- Standard returns: 8% restocking fee on the item price before tax and shipping. Shipping is not refunded in either direction. All waived if the item is defective or we made the error.
- Fitment guaranteed: select your vehicle above, or confirm fitment with us in writing before you order. If the part shows as a fit and it is wrong, the return is on us, even after installation. Otherwise, installed or used parts cannot be returned.
- Final sale: special orders, coilovers, electronics, engine internals, turbochargers, superchargers and turbo kits, unless defective or we sent the wrong item.
- Product images may be representative. The SKU and specifications in the listing are what ships.
- Email us for return authorization before shipping anything back.
Full details: Shipping Policy · Returns & Refunds · Warranty
