V6 oil pressure on start up

I was getting low oil pressure in the rocks when its hot out and my jeeps crawling at 700rpm. I know one solution is to turn up the idle, but i opted to fill it with 10w-40. My oil pressure is great now except at start-up. It takes a good 5,6 or 7 seconds to get oil pressure when I start the motor. I never really noticed how long it takes when I was running 10w-30 but it sounds like 5 to 7 seconds is a ridiculously long time with no oil. I got two questions, is it a long time with no oil, or is it typical? and is it a no-no to run 10w-40? did a lot of searching on the internet but noone answers these questions like you guys. thanks in advance

 

how do you know how long it takes?
Mechanical or electrical gauge?

 

mechanical. counted 7 seconds today

 

What brand oil filter? Some brands drain back and others don't. Pretty sure a Wix has an anti-drainback valve.

 

How long does it sit between start ups when you started counting? If a couple days or a week, no big deal. Especially if running a filter with a weak or no drain back valve.

 

I don't see that as being a problem. It is pretty typical with mechanical gages. If you want to see a faster reading, switch to a sending unit and an electrical gauge. Even if you have a filter with a check valve in it, the tubing on the gauge goes straight into an oil passage. Every time you shut the engine off, the oil drains back down. When you start the engine, all you are seeing is how long it takes the oil to re-pressurize the gauge. Wait until winter and you will probably see close to 10 seconds.

 

Hmm. This is pretty much backwards from my prior understanding and experience. Typically the response time for electric OP gauges is much longer than a mechanical gauge. The mechanical gauge should provide nearly instant feedback - the S-W gauge on my CJ-5 was quick from idle, like a tachometer. The oil will not drain from the sensor tube, and does not travel back to the engine when the engine is shut off. The tube is more like a brake line - very little oil moves in the tube - instead, the oil in the tube just transfers the pressure from one end to the other, where it's seen on the gauge. The only lag would be the propagation time of the pressure wave up the tube - again, nearly instantaneous.

You can tell by the sound of the engine when the oil pressure comes up. On start-up, you'll hear some clatter (the lifters), which should go away almost immediately as the oil pressure rises. Compare what you hear to what you see on the gauge - they should match pretty well.

 

I would second timgr about gauges.

As for 10-40, okay in summer maybe, but in a similar situation I learned that when the weather turned in a mid-winter cold snap, my engine wouldn't crank over. The oil was like glue at extreme low temps.

 

10w40 shouldn't be like "glue" in low temps-it's a base weight 10 oil.
30 years ago practically everything used 10w40...

 

first off you guys are great and have helped me so much in the last several years of trying to buy and fix old jeeps by myself with no experience. I appreciate everyone on here. you can tell the passion and dedication you all have when compared to other forums. it all started for me when my mother passed away several years ago and I see pictures and remember stories of her cj5 with a factory 304. i didn't know anything about them but I wanted one. I spontaneously bought an old cj-5 and fell in love with it. the jeep bug bit quick. a big thank you to all of you

OK, I forgot to mention that I can hear the lifters clattering the entire time until the gauge registers. Once the gauge shoots up to 50 psi, the motor starts to sound like a beautiful symphony. I agree with using 10w 30 in the winter, i just don't think it was cutting it in the hot summer days of crawling. I also threw some lucas oil stabilizer in there. don't know if its good stuff or not but it got quite a reputation from truckers my brother works with and I know its real thick stuff.

so 7 seconds is pretty much normal? i just wasn't sure at all if listening to the lifters clattering was a time bomb about to go off some day. and it will take 7 seconds if I start it in the afternoon, then run it again in the evening. I'll tell you these dauntless motors are absolutely incredible. I'm sold. wasn't sure what to expect. it sat in a barn for a decade or two. i welded in the mounts myself. put a t-18 behind it. made the driveshaft by eye. It fires right up, runs and sounds great. i did 90 the other day smooth as silk. and the power in this little jeep blows my mind everyday ok sorry about the ranting. thanks guys

PS i have a napa filter.probably a premium or something like that, i'd have to scrape the mud off I usually cheap out on oil filters for my cars and just change them regularly. but I wanted something nice for my dauntless. any recommendations other then a napa? i never heard of Wix.

 

If you get the NAPA premium line, they're good filters. I know O'reillys carries Wix. I run AC Delco on mine.

 

The worst I've seen is about 20 seconds. Mojave desert in January. Cold snap, woke to a 19 degree morning. The Dauntless fired right up but was making a racket. Eyes glued to the oil pressure gauge (mechanical), the needle finally responded and made a s-l-o-w climb to 40 PSI at which time I resumed breathing.

I have a habit of training my eyes on the oil pressure gauge anytime I start the motor.

 

When we were disassembling my oddfire for rebuild, we found that the check valve (where you screw the oil filter on) was stuck open. It would cause my oil light to come on when cold starting, until I hit the gas a little. Then, the light would go out.