If the lifters bled down while driving and the oil light is on you have an oil pressure problem. It may been brought on by extended high speed driving or some other condition but at some point it needs to be evaluated and fixed. If your engine has been neglected to the point that any type of flush or cleaner will actually work it may also be at the point that the same flush will finish the job. Try an oil change with new filter being sure the oil level is correct and use a proper oil something with 50 as the last number. Be sure not to overfill. Have a shop test the oil pressure cold and hot. If the engine sounds good you may be able to increase oil pressure by installing an oversized oil pump. Depending on the pressure switch actually installed you only have 2-3 psi when that light turns on. Even on a hot engine 6-10 would be normal at idle. 

Dennis
 

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Tyler Hardison
Sent: Friday, August 14, 2015 1:07 PM
To: vanagon@GERRY.VANAGON.COM
Subject: From flickering oil light to valves clacking

So last night when we pulled into Walla Walla, we noticed the engine was noticeably louder. Like the noise when the valves have temporarily lost hydraulic pressure.

There was no noticeable power loss, just noisy and disconcerting.

Does anyone have recommendations for a friendly Vanagon shop in Walla Walla? I think it might be time to have an engine flush with ATF or Sea Foam. But I want the help of someone who knows the engine.