Hey Whats up guys...well...i have a 94 auto z28....i was going through the posts and found that a lot and most owners used
10-30w syn mobil 1 with mobil 1 filter. Previously i was using
20-50 valvoline vr-1 racing oil and my oil pressure never went below 20psi even when i was at a standstill and car went over 240 degrees and then the fan cames on...more confusing was that it will leak oil but 2 - 3 drips overnight. I changed to Mobil 1 since it was reccomended ( 10-30w ) and my oil pressure dropped and now it leaks oil if i leave it like standing for over 3 hours and its a pretty decent puddle. Would you reccomend i just go back with the previous oil or a thicker oil???...i am not sure what to do at this point besides fixing the oil which is digging into my empty pocket. also, with this new oil when its at WOT from a standstill it will lag at the beggining about 1/2 sec before it kicks in..not sure if its the low oil pressure but i didnt have this wth the
previous oil....can a can of "fix oil leak" at autozone help it???....
I appreciate everyones response...THANKS!!!!!!!!

 

If your previous oil was working good for you just go back to it .Why ask for problems.Did you tighten your oil filter and oil pan screw well.





NICK

 

How about going halfway between the two oils, and going with 10w40 Redline or 10w40 Amsoil?

 

A lot of older cars can not be switched to synthetic oil from conventional oil. I've seen the oil just pour out of the seals. I don't understand why the syn. does it. I would suggest you try the high mileage oils that treat the seals like valvoline max-life and stay away from anything that seals leaks.

 

Your oil pressure can drop due to the thinner oil..But you should only really see the drop at idle.

You could burn more oil switching to synthetic due to the syn oil is made up of smaller molecules getting past the rings. But I honestly do not believe synthetic oil will leak through the "seals" more than conventional.. That is silly. If you have a seal leaking, iot will leak with whatever oil you are using. I would check your oil filter, drain plug for your oil leak problems if it occured right after the oil change.

 

Synthetic oil does not CAUSE leaks!!!!!!! Also, just for the original poster, they make a high mileage formula full synthetic

 

just going back to thicker oil or a heavier weight is like putting a band-aid on a bullet hole imo. i would fix whatever the problem is. Where is it leaking from?

 

The molecules of synthetic oil are quite a bit smaller than those of conventional oil, therefore synthetic can penetrate deeper into metal (the reason that it protects better), but this is kind of a catch-22 due to the fact that if you have any existing leaks they are going to be made worse by synthetic oil because their smaller molecules penetrate the seals, gaskets, etc more than conventional, hence more oil gets past these seals. So if you have a leak you do not want to switch to synthetic. I would recommend going back to conventional oil and if you would like to run synthetic in the future fix the leak, which is probably an intake manifold leak. Very common on 94 Z28's, when I bought mine in 98, the dealership fixed it free of charge because the wrong type of sealant was used on the intake manifold gasket from the factory. Hope this helped,

Derek

 

Thanks a lot for your input guys... I am going to go and buy some
Valvoline vr-1 racing 20-50 and just stick with that because earlier i also noticed on idle my oil pressure dropped to like 10psi and usually with the Valvoline oil on idle and when temperature
was up it would be at 20psi. .....
ohh..one more question....you said the factory dealer repaired the manifold leak because the wrong type of sealant was used on the intake manifold...do they still do this or was this done a long time ago??? I figure your car was probably under manuf. warranty......i am like the 3rd owner too ....
thanks for the help and i greatly appreciate........
.
oh yeah..one more thing..since the oil pressure is lower when i give it 1/2 throttle from a start it lags it and then feels like it stumbles between 2k and 3k rpm so this is another reason for going back with valvoline oil...
.

 

Well see the story on my intake manifold leak repair was when I bought the car used in '98 (it was not under warranty since its a 94), I took it home and drove it for like a week and noticed a couple of problems including the intake manifold leak, loose door handle, couple of directions on power seats didn't work. So I took it back to the dealership and they agreed to fix all the problems free of charge because they guaranteed their used cars had been inspected and any problems they had were fixed. If there has been a recall issued for the intake manifold leak I would think you can take it to any Chevy dealership and get it fixed for free, but I really have no idea if there has been a recall for this or not, maybe someone knows.... If not, there are many people on this board who have done it themselves and there might even be a write-up floating around somewhere on how to do it.

Derek

 

Thanks a lot Derek for the info...
I went and bought some 15-30 mobil 1 oil and i am going to try this to see if the oil pressure rises and maybe the leak minimizes and hopefully it will work bettter.....i'll look around the net for
any recalls on the manifold oil leak,,,
thanks..........

 

hi guys
I'm a little puzzeled, by the types of oils you are using, I thoght with these cars & engines that the oil to use was 5w-30?
can someone explain this to me
thanks

 

I wouldnt feel comfortable knowing I have a leak and just covering it up with a differnt oil. I'd fix it now before it gets any worse.

 

I used Havoline 10W-30 up until I had about 65,000 miles and then I switched to Mobil 1 10W-30 and have been using it ever since, with my Z now having 101,000 miles. I prefer 10W-30 just based on past experiences, it is what I (and my family) have used in all of our vehicles over the years and never had any problems, 5W-30 is just a little too thin for me, I think 10W-30 is a good medium oil.

Derek

 

well i changed my oil from mobil 1 10-30syn to mobil1 15w-50syn and my oil pressure rose about 5psi which is good but there is still a little hesitation at start up because of the low oil pressure so i think the rest of my engines life will be 20-50 vr-1 racing oil cuz with this oil i never had the hesitation problem and my oil pressure never dropped 20psi while on idle and it only leaked about 1 -2 drops a day compared to a puddle with synthetic ........