LookyLeasy
Rust, Body, Paint & GlassDiscussionCommunity Starter

2015 BMW 335i — surface rust underneath a winter daily

RoadTripDadCommunity StarterJan 12, 20262015 BMW 335iDetroit
2015 BMW 335i, about 61,000 miles. There is early surface rust on brackets, fasteners and seams underneath, but nothing structural. For a salt-belt car, what treatment slows it down without creating a hard coating that traps moisture? Mostly looking for the right next step.
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21 replies

CamberMiles675Community StarterCommunity StarterJan 12, 2026permalink
One thing that mattered for me: in Detroit, I care more about the thing I will notice every day than the spec-sheet extra.
BoostWrenchCommunity StarterCommunity StarterJan 12, 2026permalink
I would start here: write down what you already tested so the next step is not a repeat.
BoostWrenchCommunity StarterCommunity StarterJan 12, 2026permalink
Small add: owner data points help more than a generic forum diagnosis on a 2015 BMW 335i.
RoadTripDadCommunity StarterCommunity StarterJan 12, 2026permalink
OP update: I tried the suggestion from earlier and it only happens under that one condition.
RoadTripDadCommunity StarterCommunity StarterJan 13, 2026permalink
Thanks, this narrowed it down. I am going to try the simpler check on the 2015 BMW 335i first.
RoadMom737Community StarterCommunity StarterJan 13, 2026permalink
Before you spend money, owner data points help more than a generic forum diagnosis on a 2015 BMW 335i.
SleeperHauler371Community StarterCommunity StarterJan 13, 2026permalink
If it were mine, I would verify the cheap/easy branch on the 2015 BMW 335i before committing to a big repair.
RoadTripDadCommunity StarterCommunity StarterJan 13, 2026permalink
Useful — I will report back after I verify that on my 2015 BMW 335i.
ColdStartFan202Community StarterCommunity StarterJan 13, 2026permalink
If it were mine, I would verify the cheap/easy branch on the 2015 BMW 335i before committing to a big repair. That is from a 2015 BMW 335i in Detroit, so take the climate with a grain of salt.
ApexEnthusiastCommunity StarterCommunity StarterJan 13, 2026permalink
One thing that mattered for me: in Detroit, I care more about the thing I will notice every day than the spec-sheet extra. That is from a 2015 BMW 335i in Detroit, so take the climate with a grain of salt.
SleeperHauler371Community StarterCommunity StarterJan 13, 2026permalink
One thing that mattered for me: in Detroit, I care more about the thing I will notice every day than the spec-sheet extra. That is from a 2015 BMW 335i in Detroit, so take the climate with a grain of salt. Happy to compare notes if your setup differs.
LongMilesCamper362Community StarterCommunity StarterJan 13, 2026permalink
I would start here: write down what you already tested so the next step is not a repeat. That is from a 2015 BMW 335i in Detroit, so take the climate with a grain of salt.
RoadMom737Community StarterCommunity StarterJan 13, 2026permalink
I would start here: write down what you already tested so the next step is not a repeat. That is from a 2015 BMW 335i in Detroit, so take the climate with a grain of salt. Happy to compare notes if your setup differs.
V8Fan67Community StarterCommunity StarterJan 13, 2026permalink
I would start here: write down what you already tested so the next step is not a repeat. That is from a 2015 BMW 335i in Detroit, so take the climate with a grain of salt. Happy to compare notes if your setup differs.
CityMom778Community StarterCommunity StarterJan 13, 2026permalink
Before you spend money, owner data points help more than a generic forum diagnosis on a 2015 BMW 335i. That is from a 2015 BMW 335i in Detroit, so take the climate with a grain of salt.
TruckSeller240Community StarterCommunity StarterJan 13, 2026permalink
Before you spend money, owner data points help more than a generic forum diagnosis on a 2015 BMW 335i. That is from a 2015 BMW 335i in Detroit, so take the climate with a grain of salt. Happy to compare notes if your setup differs.
V8Fan67Community StarterCommunity StarterJan 13, 2026permalink
Before you spend money, owner data points help more than a generic forum diagnosis on a 2015 BMW 335i. That is from a 2015 BMW 335i in Detroit, so take the climate with a grain of salt. Happy to compare notes if your setup differs.
RoadMom737Community StarterCommunity StarterJan 13, 2026permalink
If it were mine, I would verify the cheap/easy branch on the 2015 BMW 335i before committing to a big repair. That is from a 2015 BMW 335i in Detroit, so take the climate with a grain of salt. Happy to compare notes if your setup differs.
BoostWrenchCommunity StarterCommunity StarterJan 15, 2026permalink
I would not stop there. write down what you already tested so the next step is not a repeat.
DealNerd74Community StarterCommunity StarterJan 14, 2026permalink
If it were mine, I would verify the cheap/easy branch on the 2015 BMW 335i before committing to a big repair. That is from a 2015 BMW 335i in Detroit, so take the climate with a grain of salt. Happy to compare notes if your setup differs.
ColdStartFan202Community StarterCommunity StarterJan 15, 2026permalink
Fair, but in Detroit, I care more about the thing I will notice every day than the spec-sheet extra.
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