NEED HELP Feedback on this plan for low oil pressure reading

[crimecanine]

Summary: Because of intermittent low oil pressure displayed especially at idle while hot and resolved by revving, my plan is as follows:
(1) Clean the throttle body,
(2) If problem persists, then replace the oil pressure switch,
(3) If problem persists, then connect a pressure gauge.

I've read many threads here. I'd like feedback on this plan. I.e., would you suggest proceeding differently?

If the problem doesn't reappear after cleaning the throttle body, then would you recommend going ahead with any further steps, e.g. replacing the pressure switch, or just monitor?

Details:

• 2002 Envoy, 4.2L, original owner, 173,000 miles.
• Several times (e.g. 7/26/2021, 3/8/2023, 7/27/2023, 8/22/2024) especially at idle while hot (weather and engine), the instrument panel oil pressure display (fake value, I know) has dropped to zero and shown "check gauges."
• Usually revving the engine in neutral makes those problems go away.
• I usually use Amsoil 0W-30 or possibly 5W-30. I understand that this low viscosity might contribute to the oil pressure switch reporting no pressure.
• It has the Amsoil remote filter kit (full-flow and bypass filters), with adapter mounted where the stock oil filter goes. (See photo.)
• I have not cleaned the throttle body. See photo from 151,000 mi (when I replaced spark plugs). I understand that dirty TB can cause low idle, thus possibly oil pressure low enough to cause the switch to report no pressure.
• I read that the oil pressure switch is bad 99% of the time (per posts by Mooseman).
• Because of this headache and an unrelated suspension problem, the vehicle has been sitting for about 1 year.

Additional comments/questions:

• Whenever I drain the oil, I'm interested in using my steerable boroscope to try to check the oil pickup screen for being clogged by carbon flakes. I saw a post mentioning that but haven't seen success.
• Because low oil viscosity may apparently contribute to low oil pressure, I'm thinking of changing to 5W-30 or 10W-30, possibly Valvoline Restore & Protect (R&P) like in my other vehicles. I'm near Houston, Texas.
• I see the oil pressure switch is $43 at Rockauto.

 

[Mooseman]

Sounds like a good plan. The dirty TB might be contributing if your idle is lower than normal, especially with the AC on, and results with lower oil pressure. And it's basically a free fix to attempt.

However I would still replace the switch as even a little lower idle speed shouldn't be triggering low oil pressure unless the engine is heavily worn.

All else fails, connect a mechanical gauge to gauge the health of the internals, either a dirty pickup, a broken pickup o-ring seal or worn bearings.

 

[crimecanine]

However I would still replace the switch...

Does a $23 Delphi from eBay sound legit?
Or just get the $43 from Rockauto?

Thanks for your thoughts!

 

[Mooseman]

You mean fleaBay? No. Likely a fake that will fail in short order or not work at all. Go for the real thing.

 

[crimecanine]

Summary: Because of intermittent low oil pressure displayed especially at idle while hot and resolved by revving, my plan is as follows:
(1) Clean the throttle body,
(2) If problem persists, then replace the oil pressure switch,
(3) If problem persists, then connect a pressure gauge.

UPDATE: The problem seems solved.

(1) Clean the throttle body =>
DONE. No difference noted, but I was glad to do it.

(2) If problem persists, then replace the oil pressure switch =>
DONE and apparently successful.
There was oil in the electrical connection of the old switch. That may have been the source of the oil drips in the area.
With the new switch, during 80 minutes of errands driving 12 miles in 80-90F weather, I did not see the oil pressure display misbehave. AC Delco D1843A was $43 from Rockauto.

(3) If the problem had recurred, my next possibilities included the following:
(a) Connect a pressure gauge.
(b) Examine the screen of the oil pickup tube for clogging. Details: Drain engine oil into a clean container. Use a boroscope to look at the screen of the oil pickup tube. If it's clogged, then pour about a gallon of parts cleaner down the dipstick tube to soak for a while, maybe rocking the vehicle occasionally. Drain into a clean container. Re-examine with the boroscope and possibly repeat as appropriate. Refill with the old oil to flush the cleaner. Drain and refill with new oil and filter. (These notional steps are from reading various Youtube comments.)

NOTES:
It was difficult to use vise-grip pliers from below, because my adapter for remote oil filters partially blocked access to the flats of the pressure switch. Therefore I accessed the switch from above by removing the air filter and the windshield washer fluid reservoir (not bad) (see photos). Then I used vise grips to break the old pressure switch loose (i.e. start unscrewing it).
To install the new switch, its thread sealant caused too much resistance for me to tighten it by hand, and vise grips from the top were too crowded, so I used channel-lock pliers from below.
In hindsight, a 27 mm deep socket or Lisle 13250 oil pressure sensor socket probably would have been worth it.

Thanks, guys!