Sharing this in case it saves another 2.7T owner a headache.

I have a 2022 Silverado 1500 with the 2.7L Turbo, currently around 51k miles.

Oil consumption / low oil issue

The owner’s manual says to check and replace the oil around 7,500 miles. I was still under that mileage and less than 5 months from my last oil change, so I assumed I was fine.

Then the engine started making a rattle during cold starts and at idle. The oil pressure gauge was also fluctuating more than normal between 15-50 but stabilized once everything warmed up.

I took it to the dealer and they found the truck was 3.5 quarts low on oil. No leaks, no obvious smoke, nothing that would have made me think it was that low (other than obviously checking the oil level myself).

When I asked how that could happen, the service advisor pointed to a GM bulletin/spec saying GM considers oil consumption of up to 1 quart per 2,000 miles to be within normal operating range.

So, doing the math, over a 7,500-mile interval, GM could consider roughly 3.75 quarts of oil consumption normal. Since mine was only 3.5 quarts low, it was not treated as a warranty issue.

The remaining oil was extremely degraded, likely because the engine and turbo were running with way less oil than expected. After an oil change the rattle went away, the dealer seemed unconcerned about long term damage so we'll see.

When I picked the truck up, the dealer put a 4,000-mile oil change sticker on the windshield and the advisor said he wouldn't go over that with this truck.

YMMV but the main takeaway: don’t just rely on the 7,500-mile interval or the oil life monitor. Check the dipstick between oil changes.

HPFP issue and weird transmission behavior

Separate but related timing-wise: the truck shook badly at idle and threw Service ESC, ABS, and Engine Power Reduced warnings. This caused me to tow the truck into the dealer.

That ended up being a failing high-pressure fuel pump, with code P228D.

Before the fuel pump was replaced, I was also getting a lot of gear hunting around 20–30 mph, along with harsh shifts. After the HPFP was replaced, the gear hunting completely went away.

My understanding is that the transmission is relying on predictable engine torque/load data to shift properly. If the engine is starving for fuel or sending erratic load data, the transmission can get confused. The harsh shifting is still there (especially 1-2/2-1 on cold starts), which may just be the normal 8-speed issue, but the gear hunting stopped after the fuel pump was fixed.

TL;DR

If you have a 2.7T, check your oil level regularly even if you are under the manual’s 7,500-mile interval. GM’s acceptable oil consumption spec is high enough that you can be several quarts low and still technically be considered within spec.

Also, if your truck is hunting for gears and you have engine/fuel-related codes, don’t assume the transmission is the root cause. In my case, the failing HPFP appears to have been causing the gear hunting.