I realized today that it's been about 3 months and almost 3000 miles since the Z's last oil change. However, this oil change happened the day before I bought it, so I don't know what type or brand of oil the old owner had put in it. I also lost his phone number.

So, the question is: what type (dino/synthetic) and brand of oil should I use? I want to run Mobil 1, but my intake manifold gasket is leaking. Would the problem get worse by running synthetic? Would it hurt the car to run dino oil in it if the last owner had synthetic? Is there a way to figure out what kind of oil is in there?

Thanks in advance!

 

Doesn't matter what kind of oil was previously used... I would personaly use Mobil 1 synthetic and just keep an eye on your intake manifold and your oil level. I don't think there is any way to see what kind of oil was previously used... if it was synthetic and you want to run dino... go for it. No harm in that. And visa versa.

Trevor

 

Synthetic can increase the leak coming from the intake due to the flowing of it. There are less impurities in synthetic than dino which can actully block up leaks a little bit. Still use synthetic though, I bet your oil level won't even go down between changes.

 

i have heard that u should only run synthetic if that is all that has ever been run through the car. if it has higher mielage i wouldnt recommend it. i would just run regular old Mobile 1 oil. it works fine in mine with 130,000 miles. oil pressure is always at or above 40 PSI

 

You can change between oils as much as you want and anytime you want. Syntetic is better for all applications no matter what the mileage.

 

Do a search on this. guys will debate this thing to the end. Basically run which ever oil you want. Just stay in the Vis range. I personally run Mobil 1 10-40 in there that should be fine. Some guys say it will leak and some will say it doesn't. You make the call.

 

Thanks to everyone who replied. I guess I'll try Mobil 1; I figure if it leaks all over the place, it won't be a big deal, since I'm getting the manifold leak fixed shortly.

 

Here is the deal with oils, it does not matter at all what brand you use as long as it is a brand name, you can put in Castrol GTX one time with a Purolator filter and Vavoline with a NAPA filter the next time, Quaker State with a ACDelco filter and on and on and on. As long as you are getting fresh clean oil in there every 3,000 miles your engine will live a fairly happy life. Now for the sythentic debate. IT will NOT create leaks so to speak, it will reveal them, synthetic has a high detergency level to it and it will take away particals left behind by conventional oils. Even tho it may reveal them, it could also treat them, my engine ol' 88 IROC with a 305 had the typical smoke on start up from worn valve stem seals, i used 5w-30 Mobil1 and the smoke got less and less each time i started it and now it is gone. You can go back and forth between synthetic and conventional as much as you want, but the biggest issue here is changing the oil every 3,000 miles(and stay away from FRAM filters)

If you don't belive me, go look on the side of a M1 can, it says that it is compatiable with all other oils and is proven safe for engine seals. The idea of not switching to Synth on an older conventional oil engine is an urban myth, i just bought my 95Z and i already have switched it over to M1, there is a leak up at the from on the oil pan (before the switch) and the M1 might just swell the seal enough to stop it.

M1

 

One this that i don't total get yet is everyone saying the M1 oils are really thin, can anyone give me more info on this likw what is the 10w-30 like? where did this information come from is there some publication that is can read this information at or is sometime a rumer that tends to fly around message boards, i am not flaming anyone but this is the first i have ever heard it and it just does not make sense to me.

 

It is true, Mobil 1 10w30 and 5w30 are both formulated on the thin side.

In order for an oil to have the second number in it's viscosity rating labelled a 30wt, it must have a viscosity at 100C of between 9.3 to 12.5 centistokes. Mobil 1's 5w30 and 10w30 both come in at 10cst, which as you can see is on the thin end of the scale.

In my observations, the LT1 engine likes an oil at the higher end of this scale. This is why I recently saw my best wear numbers (through oil analysis) using the new German made Castrol Syntec 0w30, because it's formulated at 12.2 cst at 100c, so it's at the very high end of the 30wt range and can protect the engine much better.

 

If you start running synthetic, stay with it. Don't change back to conventional.

Also, I second the opinion that Fram oil filters suck, ecxept for their $10 oil filter which is comporable to a $3 AC Delco filter. This might help you on your Oil filter choice.

 

This may be on or off topic, but Has anyone realized that Mobile 1 stoped making the M1-202 oil Filters? Does anyone know what the replacement is? I ended up buying a K&N unfortunately.

BTW Fram filters are made for those do it at home...not becasue I like to work on cars...but becasue I'm cheap people.

 

Why do you say unfortunately? The K&N oil filter is a much better choice than the Mobil 1! They are both made by the same company, but the K&N is geared for higher flow, which is much more critical in a hard driven car.

I'm using the K&N oil filter in my cars, and prefer these filters over anything else out there right now.

I use the longer HP3002 in my Firebird.

 

I just like to keep everything mobile.