Hey everyone. Well I did my first oil change on the Trailblazer and spent almost 4 hours on it. I bought 2 big jugs of Mobil1 5W30 earlier (since Walmart had no quarts of it and also to keep an emergency supply in the truck). I realize that the book says 7 quarts capacity for the 4.2L. I drained the oil and removed the filter (which was really really difficult. Ended up falling against the suspension and pouring oil all over the place including the front axle actuator). I put the plug back in and filled the oil filter (As I do during all oil changes so I keep all the variables as close to the same as possible so that the engine does not have to wait any longer for oil as it did before the oil change. I did spill a little oil in the process). I put the filter in and filled the engine up. I used up the entire 5 quart jug and about 2.2 quarts total from the other jug (even after filling the filter) with only the tip of the dipstick touching the oil (even when I use ramps, I never start the engine unless there is a sufficient amount of oil on the dipstick for safe operation. The whole recommendation about starting a car with less than the recommended oil and letting it idle before adding more is baloney to me.). Now the truck was at a slight nose high angle due to the ramps, but I have never had issues before with the 4.3L in the Jimmy. When I saw oil on the dipstick after adding that oil, I started it up and it started normally. Oil pressure was great (50psi). After driving it off the ramps, I noticed that the oil was past the top fill line, but I could not tell how much was on the cable part of the dipstick. I ended up putting it back on the ramps and slowly removing a half a quart via the drain plug into the empty oil container and it was just above the top still. I test drove it for 2 miles and it didn't go down at all. Pressure was the same as before the oil change and there were no warnings on the dash. I ended up taking out another QUART and it ended up at the 1/2 to 3/4 range on the dipstick. I was afraid that I did some damage to my engine from overfilling it, but how? Wouldn't I have had to add alot more than that to cause damage? It was making sort of a ticking noise from the front and bottom, but I dismissed it as normal belt or valve noise since it was doing that sometimes before the oil change and since the oil at this stage is new and thin (sometimes the Jimmy makes a bit of faint noise until I drive it after an oil change). So could I have put an expiration date on my 14k mile engine? I did drive it 20 miles back and there were no warnings and it drove normally.

 

So you checked the oil while the truck was on ramps on an angle? If so, you shouldnt do that, always check fluid levels while the vehicle is level . If you added 7.2 quarts and it says it takes 7 but there was way too much in there, then there is a chance you didnt get all the old oil out before filling. The angle that the truck was on, did it angle the truck so the drain plug was lower than the engine?

 

I did check it while it was on ramps to see if it had enough oil to safely start the engine to remove it from the ramps to do another check on level ground. When it was on the ramps, there was barely any on the dipstick. Off the ramps, it was overfilled. I used around 7.2 after spilling a bit and also filling the oil filter.


Didn't get all the old oil out? You may have a good point there. It does appear by looking at photos of the undercarriage that lifting the front end moved some of the oil away from the plug. The drain plug is toward the front of the pan on this truck.

I can't believe the design of this oil pan and oil filter setup. For an offroad vehicle, a very poor design. On the Jimmy/4.3L it is a piece of cake getting to the filter and oil drain. On the Trailblazer/4.2L, the axle goes through the oil pan and the oil filter is very hard to get to. I imagine that I won't be able to get a lift kit for this vehicle due to the design of the oil pan?

 

That's probably 7 quarts including the new empty oil filter. Most people dont put oil in the new filter before install so the manuals take that into account. But i doubt you did any damage to the engine. The one and only time i let a shop do my oil they way over filled it and i ran it like that for 2000 miles before i checked.

 

So I probably didn't damage the engine? Isn't overfilling dangerous? I think I took too much oil out actually because I checked the dipstick again yesterday and it was close to the minimum mark. I added 1/4 qt and got it to around 1/2-3/4 but the dipstick on this truck is so funny that it is hard to get a straight reading even checking it literally 10 times in a row. There are no oil leaks as far as I can tell. On the 4.2L, how much oil does it take to get from the minimum mark to the full mark?

So if the ramps caused this issue in the first place, what is the best way to do the oil change and be able to get the oil filter out? Jackstands? Ramps on front and jack up rear on jackstands?

2000 miles? How far was it overfilled? Were there any signs it was overfilled before you checked?

 

I don't generally get the big jugs of oil but I will if it's on sale. I always keep an old quart oil bottle around. Mark the side with an indelible marker at the full point for one quart. Old bottles make useful things to keep around. Can't find a funnel? Cut the bottom off one and put the top in the fill hole. Need a 1 quart measuring bottle, look at the mark. Need a washer to protect against metal chaffing around a bolt or nut, cut one out of the plastic.