Mosselman N54 Oil Thermostat 85C – essential oil temperature control for BMW 1M, 135i, 335i and Z4 35i
Reduce high oil temperatures and protect your engine with the Mosselman MSL N54 Oil Thermostat 85C. This BMW N54 oil thermostat upgrade is designed to open at 85 degrees Celsius, helping keep oil temps stable around 95 to 105 degrees Celsius depending on model. It is a proven, plug-and-play performance upgrade for road and track that improves reliability, consistency and peace of mind on tuned and stock cars alike.
If you drive a BMW 1M, 135i, 335i or Z4 35i with the N54 engine, you will know how quickly oil temperatures can climb. The factory thermostat targets roughly 120 degrees Celsius in normal use, which can mean heat soak, pulled timing and reduced performance. The MSL 85C thermostat lowers the operating window by approximately 20 degrees Celsius versus stock while still using a real thermostat element, not an always-open bypass. Warm-up time remains comparable to OEM, so it works brilliantly in British weather for daily driving and spirited use.
We have installed and used this Mosselman MSL thermostat on customer N54 cars and our own vehicles. Feedback is consistently positive, with noticeably cooler, more stable oil temperatures and improved confidence on fast road and track days. It is one of the best value reliability upgrades you can make to an N54-powered BMW.
Why choose the Mosselman MSL 85C Oil Thermostat
- 20C lower than stock – helps curb heat soak and maintain consistent power
- Real thermostat – not always-open, so you get proper oil warm-up in cold and hot climates
- Billet aluminium housing – CNC machined from a solid block for strength and durability
- Fast installation – genuine plug-and-play, typically around 30 minutes
- Ideal for tuned cars – improves reliability when running higher boost or track use
What’s included
- 1 x Mosselman N54 Oil Thermostat 85C
Recommended add-ons – not included in this listing:
- MSL Oil Thermostat Installation Kit: prevents leaks and makes fitting straightforward. Includes 2 x oil hose O-rings and 1 x rubber oil filter housing gasket.
- MSL Titanium GR5 Hex-Race Bolt Set: 3 x M8x25 bolts for a clean, corrosion-resistant finish.
Fitment and compatibility
- BMW 135i/is E82 N54
- BMW 135i E82 N55
- N55 in this chassis requires the N54 thermostat to fit
- BMW 1M E82 N54
- BMW 335i E90 E91 E92 E93 N54
- BMW 335i E90 E91 E92 E93 N55
- N55 in these models requires the N54 thermostat to fit
- BMW Z4 35i E89 N54
- BMW Z4 LCI 35i E89 N54
- BMW Z4 35is E89 N54
Fitting service
Professional installation available at Nforcd in Warwickshire. Email Sales@nforcd.com for a fitting quote and to schedule your visit. When installing this thermostat, an oil change is required at the same time.
Compatibility check before dispatch
We verify fitment prior to shipping. Provide your UK registration or the last 7 of your VIN at checkout so we can confirm the correct part for your BMW.
Part number
OTN54.T85
Key benefits for search
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Notes
- Oil change required during installation.
- The Installation Kit and Titanium Bolt Set are highly recommended and sold separately.
Manufactured by
Mosselman
