Mobil 1 301 vs 303 GMC 6.5

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Hi Folks, Long time lurker need some advice pls. By accident I put a M1-301 filter instead of the M1-303 filter on my 98 GMC 6.5 diesel. The only difference is that the 301 has a 30 PSI internal bypass valve. All I noticed is a higher steadier OPR on my factory OP guage.

Is this filter ok to keep on the truck? Thanks Guys
 
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30 PSI on the 301; what is it on the 303?
 
The 303(stock filter?) should have no bp valve as the bp is in the block on GM engines.

running that 301 would be fine as the block BP would open first if the 30 psi is higher,no sweat run er!!...
 
That's what I thought but I guess it's different for the Duramax. Mobil doesn't list PSI just that they are both bypassed. Wix x-reference for the 303 says 15 psi and for the 301 8-11 psi.
 
Just cruised through the ACDelco online catalog and they list only PF1218 or PF35L for '98 diesels, neither of which have a bypass. Mobil's catalog says you should be using an M-302 which also has no bypass.
 
Wow so no problems then...nice to know. Is there a spec advantage to use the 302 over the 303?

Do you think the oil preasure increase I am seeing is just due to using fresh RTS and MOS2 additive? It is a modest increase but it does show up on the factory guage.

Thanks for the welcome! I have learned so much from this forum over the years
 
The oil pressure increase could be just the new oil,i have a 1997 2500 6.5 and she blows some awesome OP,spec wise i hardly doubt there's a big or any difference in the two.

i have yet to find an over sized filter for this application(PF1218) i found one but it has no ADBV,witch IMO would be fine to use as these filters sit vertical.
 
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