JET951

Allen has an important point , last century Porsche 944S2 & 968 engines ( same applies to the 928 quadcam engines ) that on the lower viscosity engine oils tend to have issues , be it noisy hydraulic lifters & accelerated wear of their cam lobes & lifter faces + timing chain sprockets

I / we have seen it here since the turn of the century where owners have not bothered to read the owners manual that was printed when the last century Porsche was made

The oil viscosity page in the owners manual states from minus 10 deg Celsius ( 14 deg F ) to unlimited high ambient temp , use = 15w-50 or 20w-50

And in Australia ( where we are in Sydney ) its cool in winter , but can be hot in summer & we have seen many 944 , 944S,944S2,968 Porsche's were someone had installed a 5w-40 & when hot , meaning when the car had been driving around the city , suburbs for a few hours on a warm to hot day we notice the following }

A ) engine oil pressure warning light on at idle or very close to flickering on

B ) Top end of engine noisier than normal , meaning the hydraulic lifters have bleed down a little & are now a bit clack y , that's because the oil pressure is so low the top end is not getting sufficient oil pressure at idle

C ) The timing chain ( twin cam 16V ) becoming noticeably noisy , that's because the oil pressure at idle is so low there is not enough oil pressure to keep sufficient oil pressure within the hydraulic chain tensioner & the timing chain rattles ( not good )

A 5w-30 engine oil in our climate would be even worse

I would only use a 5w-30 if the ambient temp was no hotter than ZERO degrees Celsius ( 32 deg F ) , which means the average temp would be around minus 15 to minus 5 deg Celsius ( 5 deg F to 23 deg F)

I just got out an owners manual from a 1994 928 GTS we have here at the moment & it states quite clearly the very same thing , meaning a 5w-30 to be used ONLY up to ZERO deg Celsius MAX ambient temp

The other thing that's very important is the low Oil Film Strength of the lower viscosity oils in relation to last century High Loaded Flat Tappet design engines & the twin cam 944 & 928 are VERY high loaded flat tappet design , and that's not just the simple fact that the low viscosity engine oils is always lower in oil film strength as compared to last century higher viscosity oils if the levels of ZDDP are the same , which they never are , the very low viscosity oils like 5w-30 & most 5w-40 oils are low in ZDDP to meet the ACEA emission protocols for this century automotive engine oils , even diesel oils are having to drop the levels of ZDDP to meet stricter emission requirements for late model vehicles

Last century engine oils , like 20w-50 & some 15w-50's are higher in ZDDP ( AW additives ) because they are mainly used in last century engines ( like the 968 ) and they are allowed to use higher levels of ZDDP

First thing I would do is remove the twin cam cam cover ( rocker cover ) & inspect very carefully all the cam lobes for wear & all the camshaft centre sprockets teeth for wear

As a simple guide , we generally remove the cams on the 944S , 944S2 & 968 about every 120,000 KMs to replace the timing chain & the very important plastic guides

mel_t_vin

Exactly...what Sean said.

Sage advice designerguy90, based on empirical evidence, as Sean and Bruce have probably opened/examined hundreds of Porsche engines in their course of business.