Mishimoto MMRAD-GMT-99 Performance Aluminum Radiator, Compatible with Chevrolet Silverado, 1999-2014

Huge improvement over the factory radiator!!!! I lucked out just got home from a long drive pulling my camper and the OG plastic end cap on the radiator spilt open ! Install was way easy !!!! Everything welded great ! I can tell a difference when pulling my camper up steep grades here in Colorado!! I highly recommend this to anyone !

'03 1500HD w/6.0L & 4L85 The Good: 1. Excellent cooling performance. Temperature regulation is stabile at 192-196 degrees (scan tool indications) and my transmission temperature dropped by 25-35 degrees (gauge). 2. Fitment was perfect requiring no modifications using my Electric Fan assembly. The Bad: 1. AMAZON - sent me an obvious open box. This item had been handled previously and put back into the manufacturers packaging improperly (the box staples had been broken and the box was taped shut, the foam was randomly placed and the radiator was not secure within the box) prior to arriving at my door. This caused minor damage to the fins (both sides) which took me over an hour to straighten. I would have returned for an exchange if I had the time. 2. MANUFACTURER - the oil and transmission cooler tube adaptors were loose - not even snug (several threads away from seating). These would have leaked had I not checked them. They need to be tightened to seat the O-ring in the threaded tank bungs. 3. MANUFACTURER - Fitment issue with the oil cooler tube adaptors to the tubing - too tight - which prevented the flared tubing ends from being inserted even without the clip. I removed each adaptor from the tank and worked them against the tubing ends until they seated (rotated back and forth while pushing tube in and out) with reasonable insertion force. Another wasted hour...

I bought this item and have had to do 3 warranty replacements due to leaks from the fins. Each one lasts about a year. Customer service is great but the warranty replacements cost $100+ not including hiring a mechanic to replace the radiator. When its working it has reduced my running temp in a noticeable way while towing. Mechanic suggested I cut my losses and just buy another brand.

Vehicle: 2011 GMC Sierra 1500 (5.3L) Installed this Mishimoto all-aluminum radiator as an upgrade from the factory unit. Build quality stands out immediately—solid aluminum construction with clean, consistent welds. Fitment was correct for my application, and overall construction feels more robust than typical OEM-style radiators. Cooling performance has been strong so far. The increased capacity compared to stock helps maintain stable temperatures under load. This unit includes integrated cooling for coolant, engine oil, and transmission fluid, so it’s important to verify your specific configuration before ordering to ensure compatibility. Overall, a well-built upgrade for those looking for improved cooling and durability. Higher cost than standard replacements, but the construction and performance reflect that.

A small disclaimer, I'm still building the truck that this is going in, but I have marked it up and it fits perfectly where the stock radiator was. A direct replacement. I will update this review Once I have driven it around for a while, but looking at it, the build quality is impeccable, the Finish is beautiful, and I can't wait to show this thing off.

First off this radiator was ordered for my 2002 GMC Sierra 1500 4wd 5.3. When I received this radiator I was blown away at the quality and craftsmanship. Noticeably larger then my original factory radiator in every way. When I purchased the radiator I also purchased the black mishimoto radiator hoses I mean why not? Anyways once installing the radiator which fit perfectly without any modifications required except I did have to do some research because my existing fan shrouds were about 5” too short on each side of the radiator. Served it’s purpose as is but I wasn’t satisfied with the finished product. After a little research I ended up ordering GM Part#s 15267487 and 15088328 which are upper and lower factory fan shrouds that fit perfectly with this wider radiator. I’m very satisfied with the fitment and performance of the radiator and would definitely recommend this to anyone that is looking to upgrade your factory cooling system!

Experiencing the same issue that others have reviewed. These radiators are supposed to be worth the extra cost and these unfortunately are not. I’m on my second one and both are leaking from the upper driver side section. I have a buddy that has the same one and it’s leaking from the same location as well. Obviously a defect and all Mishimoto will do is send you another one for $100 or send you some leak stop. Unacceptable and the last Mishimoto Product I purchase. The pictures are of the two radiators I’ve used, over $800 in less than 2 years. Find a better product to spend your money on

I replaced the stock, plastic fitted radiator on my 2000 Chevy Silverado with this Mishimoto radiator. The only note to anyone looking at this product I would give, is that it is bigger than the stock, so your fan shroud will not affix to it without a little ingenuity. Other than that, this radiator is beautifully constructed, fits into the stock position and bolts right up (to the wider bolt pattern). It also holds around a gallon more fluid, which is always nice!