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2018 Cadillac CTS-V — oil level drops between services with no puddle

CanyonGal883Community StarterOct 21, 20252018 Cadillac CTS-VOrange County
2018 Cadillac CTS-V, about 95,500 miles. I started measuring the oil level every few hundred miles and it is definitely falling between changes. There is no obvious puddle and I do not notice smoke. How would you document and diagnose this instead of guessing?
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4 replies

BoxerBuilder275Community StarterCommunity StarterOct 21, 2025permalink
Ask what changed right before it started. A pressure test beats staring at a dry driveway if the 2018 Cadillac CTS-V is losing coolant with no puddle. That's the branch I'd chase this week. This is from a 2018 Cadillac CTS-V in Orange County with 95,500 miles. Not gospel, but it saved me a headache. That's coming from doing this as an owner, not a shop. Might be overthinking it, but I'd rather overthink than overspend.
HybridLearnerCommunity StarterCommunity StarterOct 21, 2025permalink
Asking because it changes the advice: Loaded-suspension checks on the 2018 Cadillac CTS-V catch play that a wheels-hanging inspection misses. You'll know quickly if you're on the wrong tree. Had a similar mess a couple years ago and that's what finally sorted it. I'd rather pay for diagnosis than a second guess-repair.
MarketGal186Community StarterCommunity StarterOct 22, 2025permalink
Same neighborhood, different next step: Swap the cheap/easy piece first on the 2018 Cadillac CTS-V and see if the fault moves. You'll know quickly if you're on the wrong tree. This is from a 2018 Cadillac CTS-V in Orange County with 95,500 miles. Write the result down so the next test isn't a repeat of the last one. I'll update if anything new shows up.
BoxerBuilder275Community StarterCommunity StarterOct 21, 2025permalink
Log the conditions before you spend. Move a coil or plug on the 2018 Cadillac CTS-V if it's cylinder-specific and see whether the code follows. Don't erase codes until someone who can help has seen them. On “v — oil level drops between services,” that was the fork that mattered for me. Take it or leave it — that's what I'd do. Cold start is when I can actually reproduce it.
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