emg32

I have owned my stock 1995 Z28 for 7 and 1/2 years now and have always used Mobil 1 Synthetic Oil and the AC Delco PF35L oil filter. I have always used the recommended 5W30 but have seen that some of you guys are using 10W30 or thicker. My Z has 70,000 miles on it and I was wondering if the 10W30 would be better for my car than the 5W30 as it gets older? I also thought about trying the K&N shorter oil filter. Which one gives you the best oil flow and filtration (PF35L or K&N)?

I was also thinking about hollowing out my caytalitic convertor. Have any of you guys did this? Does it really improve the flow and horsepower of the LT1's? Will it harm the engine at all?

Thanks

moparman

The people who have actual oil analysis performed on their LT1 engines say the best current oil for the LT1 is the German made Castrol 0W30 synthetic.

lt4 fd

Yeah I am about to try that 0w30 german syntec here in a couple thousand miles, another great oil I have used is the Schaeffers 15w40, but I wouldnt run that in the winter. I had that analized with great results after a 4300 mile interval the lab said it would be good till atleast 6000 miles. Im about to have the scheffers 10w30 analyzed which I had in it right after the 15w40 for the winter. If you want to know everything about how to choose oil and filters, fuel cleaners, oil flushes, tranny fluid, rear end fluid and any other cleaning agent or lubricant go here www.bobistheoilguy.com and little down the page on the left is a link that says forum after you read up all the main page has to offer.

As for the oil filter I use the K&N3002 which is the oversized version for our car and holds about a quart of oil, that has worked well for me and another prominant member of that forum I gave you suggested it and uses it. Its a 12 dollar filter but you get what you pay for, do a search on that site for it adn Im sure you will get a lot of info. Also gutting the cat wont hurt anything in the motor but I would leave it alone. I didnt feel a difference after I did it and wished I never had, big mess too... You wont pass inspection either, unless you are a 96 or 97 and buy O2 simulators, 100 bucks.

96capricemgr

It is specifically Mobil 1s 5w-30 that is too thin another brands 5w-30 might be a good choice Amsoil for instance. Weights only mean the oil falls into a viscosity range M1 30wts.(the 10w and 5w) both fall to the very bottom of the allowable range for a 30wt., the LT1 does better with a thick 30 to low 40 wt.. If you like M1 then just try the 0w-40 or the Truck and SUV 5w-40 either is a better choice than their 5 or 10w30, Geman Castol 0w-30 is awesome in this application as well. Please don't mistake my comments as meaning the 30wt. M1s are bad, they are not, they can be very good in some applications, unfortunately this is not one of them. On the above linked oil site I saw an increadible oil analysis for 5w-30 M1 15K in a turob 4 cylinder VW, great oil for that guys car and usage, again just not right for the LT1.

TheHeadFL

I use Mobil 1 0w40 after reading on here and elsewhere about this. Might try German Castrol 0w30 sometime.

97 Z-28

I run Royal Purple 10w30 with the K&N oil filter.

emg32

Thanks guys. Is it ok to use the 0W40 in all weather conditions or is it to thick for cold weather?

moparman

Where are you located?

emg32

Kentucky. In the summer it usually gets 90-100 degrees and in the winter 0-40 degrees. Sometimes with the wind chill it gets below 0.

I just saw that you are from KY also so you know the extreme's we have.

FastZinTennessee

I used to run the mobil 1 0w40 in my Camaro with great results. I never had an oil analysis done, but my oil pressure was a lot better with it compared to even 10w30 mobil 1. With 5w30 and 10w30 mobil 1 I got that weird oil pressure drop under wide open throttle at higher RPM. When I switched to mobil 1 0w40 the problem went almost completely away. I then finally saw 60-65 psi oil pressure at redline. I would definitely recommend the 0w40 weight. Just personal preference, but I used STP oil filters as well. It's a good compromise between filtering and flow efficiency, which is what you want. It's also a lot cheaper and readily available than the K&N.

BTW I think 0w40 would be fine where you are. I used to live in Bowling Green.

emg32

Thanks FastZinTennessee. I think I am going to try the Mobile 1 0W40. I live in Owensboro, which is about 45 miles from Bowling Green.

emg32

Do you guys use the Mobil 1 0W40 that says European Car Formula?

96capricemgr

0w-40 is only a 40wt. once the oil is hot it is the 0w part that matters for cold weather, and unless temps are below zero anything from 0-10 will work there, if below 0 then stick with 0 or 5w.

FastZinTennessee

Yes that's what I used.

BoobSter-lt1-z

I Had Problems With Low Oil Pressure Dropping After The Car Heated Up At The Drive Thru And The Fans Came On. It Would Do A Stumble Because My Oil Pressure Was At 15psi But Now With Royal Purple 10-30 It Will Not Go Below 20psi After It Heats Up And Goes Through A Fan Cycle. I Would Reccomend This Oil Also.