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Discussion Starter #1 (Edited)
Hello all. Anno Domini (AD) Elantra SE 2.0. Getting ready to do the first oil change at 3200 miles. (I can guess people are rolling up their sleeves to battle it out on the right time to do the first change, but it is not a waste of perfectly good oil, as it will be saved and used in my lawn tractors, which burn almost as much oil as gasoline....:)) Anyhow, I am about to go to Harbor Freight and pick up an oil pressure tester because I want to test OEM pressure cold, hot and revving. I then will change the oil and compare values and see if any difference. Soon (soon "in days", that is), I plan on getting a nice permanent electric oil pressure gauge from ebay and will post on that, but for now I just want to test and compare before and after the oem fluid and filter. I would like to ask if anyone here perhaps knows where I can attach such a tester (probably in the place of the oil pressure sender), and if the psi specs are known. Thanks in advance... I certainly will post my findings and pics.
 

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I think you may only notice a different pressure at idle and that's only if you use a different viscosity oil. From that point on the oil pressure relief valve starts working and regulates the pressure against a spring. Seems like a lot of mucking around but if that's your interest do it. You'll probably need to fit an adapter to run both the original sender unit and your gauge at the same time.
 

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Oil pressure switch is on the oil filter mounting pad..

Dont waste time with electric gauge, go all out with real mechanical gauge and aircraft type hardware and hose
 

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Discussion Starter #4
I think you may only notice a different pressure at idle and that's only if you use a different viscosity oil. From that point on the oil pressure relief valve starts working and regulates the pressure against a spring. Seems like a lot of mucking around but if that's your interest do it. You'll probably need to fit an adapter to run both the original sender unit and your gauge at the same time.
Didn't mention in original, but I really was more concerned about oil filter differences, as in some being more or less restrictive. For now, going with K&N filter and synthetic 5w20 after testing oem pressure, perhaps tomorrow. I will eventually go with a "wix-in-disguise" Supertech oil filter in a year or so and will report pressure difference if any, but for now since it is barely broken in, I want to catch as much fine metal as I can.
 

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Discussion Starter #5
Oil pressure switch is on the oil filter mounting pad..

Dont waste time with electric gauge, go all out with real mechanical gauge and aircraft type hardware and hose
Thanks for the info and opinion! Yes I was thinking mechanical with copper tubing and careful routing, but still too risky. Lots of horror stories of oil spraying inside the cabin from thousands of miles of vibration, behind the dash mind you, etc. With electric, worst case is a bad sender or gauge, easily replaced and clean. I'm like 70/30 in favor of electric. Heck, everything else seems to be going that route.....
 

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The threads will be BSTP 1/8" x 28. I use an adapter like this to keep the OE sender and add a NPT 1/8" x 27 port for the aftermarket gauge.



ebay

BSPT to NPT Tee 1/8" Adapter Pressure Sensor Gauge Turbo Oil Toyota Lexus L-2Y
 

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Oil pressure switch is on the oil filter mounting pad..

Dont waste time with electric gauge, go all out with real mechanical gauge and aircraft type hardware and hose
Yes, siree...and make sure those fittings don't leak!

If he was only driving it on weekends, quarter-mile at a time, mechanical not that big a deal. But I'd prefer electric. For obvious reason, stated above.
 

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Again I don't think your going to find any difference. Both the system and filter have relief and bypass valve and I firmly believe that the oil filter bypass valve is open when the oil is cold. It's a fine-line balancing act between all factors but lets see the outcomes. The only time I have ever seen a problem was on a Mazda truck that had a bypass filter as well as the std filter and straight after I changed the oil and filters he complained of the oil pressure light coming on when driving. Both filters were genuine. I found there was a pressure switch on both circuits and the bypass filter switch triggered when the pressure went too high indicating it was blocked. The spring inside the bypass valve was too strong triggering the oil light. Because of the fact it was the bypass circuit turning the light on no engine damage would have occurred but I wasn't to know that at the time.
 

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Hyundai's oil filter bypass for the screw on filter is 20 psi. That means there has to be 20psi more pressure on the input (dirty) side of the filter before the bypass opens. Maybe if the oil is very cold it would be opening. The oil pressure sensor is on the output (filtered) side of the filter.
 

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I don't feel like crawling underneath anything. I'll just trust Hyundai to have a good sending unit in the car. And if they don't? Well, they can put in a good one when they bolt that new motor to it. ;)
 

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Discussion Starter #12
Well, results are in. I got the Harbor Freight oil pressure tester for around $20 and it looked to be ok quality wise. Just ok. I do give that pressure tester high scores for all the pieces included, those parts alone are probably worth the $20. I put the car on ramps last night and started working on it this morning without turning it on. I took off the pressure sensor right above the front end the filter (thanks for the info guys!) and had absolutely no oil coming out. So much for the "anti-drainback" valve on the oem filter. I ended up using an extension, an elbow and connection from the kit to get the gauge on but lesson number 1 before going any further is to use teflon tape on threaded portions (preferably the yellow kind that is made for gasoline). I spent some time trying to get my fat fingers and hands to feel my way from under the vehicle to get the pieces used in place, only to turn on the vehicle and spring a leak again and again from a couple of those connections. Connection to the car was good, no teflon, but the other pieces needed it. They are all NPT connections in the kit, no British thread included in the kit according to the parts list. Anyhow. I laid the gauge onto the windshield so I can see it as I turn on the car. It takes 1-1.5 seconds for that gauge to jump up. Bad gauge perhaps. Every time though, on startup it would take 1-1.5 seconds to go from 0 to whatever. I found that it usually jumped to roughly 30psi on startup and then settled down to 20-21psi in a few seconds. The first startup jumped up to 72 psi, but that was because it revved up a bit being the first start of the day. After starting and driving around, it was consistent that startup and idle were between 20-21psi. If I slowly start revving, I see the gauge slowly climb up in sync to about 35psi and then suddenly pop up to 70. Odd. I'm guessing this would be the point the bypass valve lets the oil go through. This happened over and over again. I saw enough of this and changed the original oil and filter. I went with Valvoline synthetic 5w20 and a K&N filter. I then did the same testing. The results were identical. No change in the behavior of the gauge. I am pretty sure the gauge is not accurate, but I am satisfied that the testing proved identical idle and revving characteristics and range with the new oil and filter. If I raced it to 4500 rpm, the psi would follow up to around 100psi, but it was not sweeping smoothly on the gauge, so the gauge is going to be returned. Consistent idle and consistent 2k rpm would yield the same steady psi before and after oil and filter change. I am surprised at the 1-1.5 second delay in building pressure. I always thought the initial startup was almost immediate oil pressure. Lots of moving parts in 1.5 seconds...... I plan on keeping this car for well over the 100k miles, so Marvels Mystery Oil is going to go into every fillup now. I wanted to take pictures, but hands were always oily and I did not want to oil up the phone, sorry! But, I will be getting a permanent gauge, and will take pictures of that. Interesting to note, if the plug that connects to the oil pressure sensor is off, you will NOT have an oil light. When you go to start the car, it will not light up at all. You will not see a light if you break that connection. Peace all!
 

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The anti drain back valve is more to keep the filter filled.

It is not an NPT thread though very similar. With more installs and reinstall of the OE parts sooner or later the aluminum threads in the filter adapter will strip.
 

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All oil pressure lights work like that. That's why its important to always watch it come on and go out after startup. I think your gauge is miles out. 100psi oil pressure is way too high.
 

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100 psi and you should be hitting the pump bypass. The highest oil pressure I have ever seen on my Gen Coupe was around 90 psi and that was at 7500 rpm and 0w40 oil.
 

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Discussion Starter #16
Upon putting the oil sensor back, I see that the oil light goes out right at startup, actually just a split second before she fires up with the new oil and filter. So the only good info that I got from the harbor freight gauge was that the pressure before and after the oil and filter change is the same. Same wrong results. Hehe. Key is, they're the same. I think there is an inherent flaw in the gauge. It comes with like a 5 foot or so long rubber hose. A wiggly flexible rubber hose. It probably takes quite a bit of time to pressurize the air in that hose, hence the 1.5 second delay. The occasional gauge jumpiness is just the cheapo gauge I guess. Anyhow, thank you all for your input.
 

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Not necessarily it depends on the pump design. I have seen many cars having a slight pulse on the oil pressure. That's not to say your car is one of them. I haven't seen oil pressure gauges with a rubber hose. Its usually copper. I thought you were going to buy an electronic gauge. One thing to know is only takes a few psi to turn the oil pressure light off.
 

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@mirageman: Thanks for the post. Enlightening. And it reaffirmed my decision to keep my happy butt on the top side of the vehicle. I had visions of tools and misc. stuff flying thru the air when I read that part about an oil leak.

What to send me into the stratosphere? Tell me I have an oil leak :eek: and then back away. Quickly! LOL ;)
 

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Discussion Starter #19 (Edited)
Not necessarily it depends on the pump design. I have seen many cars having a slight pulse on the oil pressure. That's not to say your car is one of them. I haven't seen oil pressure gauges with a rubber hose. Its usually copper. I thought you were going to buy an electronic gauge. One thing to know is only takes a few psi to turn the oil pressure light off.
Actually, the mechanical gauge I used was just a test gauge, very similar to the gauges used to test compression. This: https://www.harborfreight.com/engine-oil-pressure-test-kit-62621.html
I still plan on getting an electric permanent one, but having trouble deciding where to put it. Not sure I want to go the A-pillar route, hmmmmm. The oil gauge I'm seriously considering is one of these:
 

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Those gauges look exactly like ones I am using. Mine are sold under the name of SAAS I think they are very accurate. I have a temp and am using an oil pressure one for fuel pressure to make sure I don't run out of pressure under boost. I have data logged and compared the engine temp with the gauge and it's spot on.
 
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