Heating and Cooling› Thermostats, Housings and Fillers

Improved

Racing Oil Cooler Thermostat

$199.00

SKU: FSM-165

Special Order
Special Order
Ships in 4–6 weeks
Free Shipping over $200
$100 Minimum Order
30 Days Return
INSTALL DIFFICULTY
DIY PRO SHOP

Moderate — 2–4 hours

Overview

The Improved Racing FSM-165 is a universal oil cooler thermostat designed to regulate fluid temperatures. It bypasses the oil cooler until 180°F (82°C) and ensures full flow through the cooler by 200°F (93°C). This helps prevent overcooling, reduces engine wear, and maintains optimal operating temperatures for performance vehicles.
Show original supplier description
The Improved Racing FSM-165 is a universal remote engine oil cooler thermostat engineered for high-performance vehicles. It addresses the issue of oil overcooling in systems with large oil coolers, which can lead to delayed engine warm-up, horsepower loss, and increased engine wear. By intelligently bypassing the oil cooler until the oil reaches an optimal operating temperature, this thermostat ensures efficient performance and longevity. Constructed from 6061-T6 billet aluminum with a durable black anodized finish, the FSM-165 is designed for reliability. Its unique internal design places the bypass valve mechanism out of the direct oil flow when closed, minimizing pressure drop. This thermostat begins to open at 180°F (82°C) and is fully open by 200°F (93°C), making it ideal for transmission and differential fluid cooling. It is also rebuildable, allowing for easy servicing and potential temperature rating changes with available kits. The FSM-165 features universal applications and is available with fittings for -8AN or -10AN lines. Included mounting brackets offer flexibility for various installation configurations. This device helps reduce excessive engine wear and horsepower losses by preventing fluid temperatures from dropping below optimal levels, and can also contribute to improved gas mileage.

Product descriptions are provided by our supplier partners and may not always be perfectly accurate. Not sure this fits? or call (760) 282-4645 and we’ll verify before you order.

Fitment

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Specifications

BrandImproved
Part NumberFSM-165
CategoryHeating and Cooling
5,000+ Trusted brands
1M+ Enthusiasts
5M+ Parts sold
(760) 282-4645 hello@motormia.co

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Returns & Fitment

Built for enthusiasts. Every order is backed by our 30 day return window on eligible items. Unused and uninstalled products may be returned with approved RMA and no restocking fees when received in new condition. Orders placed through the MOTORMIA app with a complete build qualify for our Fitment Guarantee — free return shipping if the part doesn’t fit your exact setup. The guarantee covers fit only; installation must follow manufacturer instructions, and we recommend a qualified shop for parts marked Difficulty 4–5.

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Shipping

Orders are processed in 1–3 business days. In stock parts ship promptly from our partner network. Special-order items either aren’t currently stocked or are built to your spec — expect 4–6 weeks. If a part goes on backorder while your order is in the queue, we’ll reach out and work through discounted alternatives together.

Free shipping over $200 in the continental US. Alaska, Hawaii, U.S. territories (Puerto Rico, U.S. Virgin Islands, Guam, American Samoa, and the Northern Mariana Islands), and international orders carry surcharges — most appear at checkout. Some exceptions (LTL freight, or suppliers who quote freight only after we place the order) won’t. In those cases we’ll reach out with the exact charge before your order moves forward.

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