2008 5.3L Sierra SLT Today I was going to help a friend pull his trailer, and when I was slowing down to turn in the driveway, my oil pressure gauge ...

2008 5.3L Sierra SLT

Today I was going to help a friend pull his trailer, and when I was slowing down to turn in the driveway, my oil pressure gauge bottomed out, the dash light came on, the dinger was going nuts, and the info center told me to shut the engine off immediately.

I pulled in the driveway, shut it off, checked the oil, and it was at the second to top hole in the dipstick. There wasn't any oil dripping from under the truck either. I started the truck back up and the oil pressure went up to just above 40. Then it slowly fell back to zero and the warnings went off again. I shut it off, started it again, and same thing. On the third try it stayed up around 40, fluctuated a little between 30 and 40. I drove straight home (about three miles) without a problem. I let it sit for an hour or so, and just drove it around town and it stayed above 40.

I have owned the truck for a few months now. I made the mistake of not checking the oil level until just the other day. You would think the dealer would change the oil, or at the very least top it off. I assumed wrong. I had to put 2.5 quarts in it to fill it up. There is about 18% left on the oil life meter, but I decided to get Amsoil and change it now.

I already have the Amsoil sitting here, but now I'm not sure I want to put the Amsoil in it. Especially if I need to take it to the dealer and he needs to drain it. That would be a waste of Amsoil! I'm thinking of doing another regular oil change (probably synthetic Pennzoil or something) before I go with the Amsoil, just in case there is a problem with the truck. Or just take it to the dealer as is and let them deal with it.

Any thoughts?

I thought I read on here somewhere or maybe it was'nt on here that some of the AFM 5.3L engines (assuming yours is an AFM engine) would have an issue consuming oil. Maybe some of the Sr. members will know better. I would get it into the dealer ASAP and tell them what happened. Since you added 2.5 qts is the oil pressure fine?

x2 on taking it to the dealer. could have a faulty oil pump(yikes) or just a bad sensor.

6Sixathome wrote:I thought I read on here somewhere or maybe it was'nt on here that some of the AFM 5.3L engines (assuming yours is an AFM engine) would have an issue consuming oil. Maybe some of the Sr. members will know better. I would get it into the dealer ASAP and tell them what happened. Since you added 2.5 qts is the oil pressure fine?

I am far from a senior member but i thought AFM motors became available in 2010 or maybe 2011. I am fairly sure this was not the case in 2008 but i am not up on the GMC side of things

My 07 has AFM, I am pretty sure that is the year it was first available in the trucks. However, I don't think that is the issue here. I agree with adams99z71's opinion.

My mistake....looks like afm was avalible in 08

Id b looking @.faulty pump or sending unit... other than that only sure advice is i wouldn't even put penzoil in my lawnmower....

To update, I put about 80 or 90 miles on it this weekend, and only once did the oil pressure start to fall while I was driving (only a few miles into the weekend). It slowly dropped down to around 20 while cruising at 55 mph. I put the pedal to the floor, the pressure shot up to 60 and never again went below 40.

I'm still going to take it to the dealer. I just need to find one that won't give me a P.O.S. to drive while they work on it. Thank God I got the extended warranty!

6Sixathome wrote:Since you added 2.5 qts is the oil pressure fine?

It happened after I added the oil.

camlope31 wrote:other than that only sure advice is i wouldn't even put penzoil in my lawnmower....

To each his own I ran Pennzoil Platinum in my 2001 Jimmy 4.3L until I traded it in at 138K miles, and never had a problem.

I'd lay money on the sending unit since it's electrical and more likely to give a false intermittent reading wear as the oil pump is mechanical and in my opinion would have a constant/non intermittent reading.

So, any update as to the actual cause? My '05 is doing this and I'm researching to find a cause/solution.