When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
Hi, I recently changed the oil and oil filter on my 90’camaro with 305 tbi. Car is all all original and has under 100k on it.
The gauge always read between 30-55 range depending on rpm and temp. Now at idle when warm on a 95 degree day the gauge reads slightly above the first yellow line on the left (at idle) and goes to 30 when at freeway speed or under acceleration. I used a good wix oil filter from Napa and bought the oil there too. I used the 5-30 weight which is what is specified on the oil filler cap. Anyone had this experience before?
Good advice GD.........But.....weather or not his gauge is accurate or not, he still isn't getting the reading he used too. Just saying
And , since the OP says he put in 5W-30 , we gotta ask what was in it before , if it was 10W-40 or even 20W-50 that could explain the different reading .
And , since the OP says he put in 5W-30 , we gotta ask what was in it before , if it was 10W-40 or even 20W-50 that could explain the different reading .
Nope,nothing has changed. I’ve used the specified 5-30 weight each time I’ve changed the oil.
I can replace the filter again,but used the Napa gold filter which is made by wix. Never had this issue before.
if I spin off the oil filter without changing the oil first,how much oil will be lost?
Makes no difference. Filter is above the oil level in the pan. You will lose around half a quart to 1 quart depending on what size filter you are running.
The filter is unlikely to change anything but you may as well try. While you are buying a filter get a mechanical gauge to check the actual pressure.
I mentioned the filter because nothing else has changed if the same viscosity of oil was used. There's no other reason for a sudden drop in oil pressure from one start to the next...
Agree,unless the pressure sender is going bad,but I don’t see why that would happen after the oil change either. Thanks everyone for the advice. I just wondered if anyone else had this issue before.
Check the owner's manual. Despite the fact that "5W-30" may be printed on the fill cap, but the manual lists the appropriate viscosity at a given ambient temperature range. You may find that 10W-30 is more appropriate.
Thanks Vader,I plan on changing the oil again this weekend and filter and using 10-30 since it’s hot out here. I have no idea why they specific 5-30 anyway. Guess that must have been a later third gen thing. How common is it for the filter to be defective and cause low pressure,or for the sender to fail and give a low reading?
Where is the port for a mechanical oil gauge to test it anyway?
5w30 vs 10w30 isn't going to make any significant difference. That's a tiny change any only when it's freezing outside. They are both 30 at operating temp. Depending on load requirements I will use 40 or 50 at times on otherwise similar engines. BMW calls for 60 on their M series cars. The Ford Focus RS calls for 5w50..... clearances in the engine are not altered for changes in viscosity. It's just a matter of what kind of loads the bearings will see.
You can either tap into the existing gauge sender port, or the switch port above the oil filter mount. Whichever you prefer.
Well I changed the filter and it still reads the same. Here’s where it’s reading at idle in gear fully warmed up. Like I said it read over to the right prior to my changing the oil about a couple weeks back. I’ve just changed the filter again and it’s the same,so I have no idea if the sender has just gone bad or what. There’s no litter noise at all. Engine runs smooth and quiet.
Where do these cars normally read on their factory gauges?
On my L98 that I run Mobil 1 5w-30 I typically read around 60psi while driving and when I stop and idle it typically is at 30psi with the factory dash gauge. If really warm or car has been ran awhile will hit like 28-29 at idle. I replaced the oil pressure sending unit last year because the oil pressure was constantly pegged and now it seems to work correctly...how accurate that is who knows with the factory gauges.
The sender is not that expensive or very difficult to change, might be worth a shot. At the least check the wire to it and see if its loose/damaged.
On my L98 that I run Mobil 1 5w-30 I typically read around 60psi while driving and when I stop and idle it typically is at 30psi with the factory dash gauge. If really warm or car has been ran awhile will hit like 28-29 at idle. I replaced the oil pressure sending unit last year because the oil pressure was constantly pegged and now it seems to work correctly...how accurate that is who knows with the factory gauges.
The sender is not that expensive or very difficult to change, might be worth a shot. At the least check the wire to it and see if its loose/damaged.
Thanks red dragon. My gauge always used to be between the 30 and 60 when I was driving and then it idle it would go to 30
09-24-2020, 09:06 AM
And , since the OP says he put in 5W-30 , we gotta ask what was in it before , if it was 10W-40 or even 20W-50 that could explain the different reading . 
