Need help - which oil for Northstar Flat Tappet?

[ekpolk]

Originally Posted By: abs
. . .
epolk - can you point me to any stats on the Mobil 10W30 HM? Does it have a lot of ZDDP and/or is it API certified with a newer spec?

Regards,

Andrew


Andrew:

While on one hand, Mobil does put a lot of info on its PDSs, they're inconsistent from one to another. Some have stats for Zinc and Phosphorous. Others don't -- including this one. FWIW, it does have a high HTHS, and it's SL, SJ, but NOT SM. That has to be a good sign for you.

Click here for Mobil 1 10w30 PDS.

 

[daman]

Originally Posted By: abs
epolk - can you point me to any stats on the Mobil 10W30 HM? Does it have a lot of ZDDP and/or is it API certified with a newer spec?

Mobil 1's 10w30HM API SL has a nice slug of zinc;

zinc 1000 PPM

OR you could run Mobil 1 Turbo Diesel Truck 5w40 witch has;

zinc 1200

OR 0w40

zinc 1100

so you see you have many good choices that would all work great in that engine

 

[abs]

Okay, some interesting options listed, thanks ekpolk and damon! I still have some concerns though. I think the zinc levels need to be up around 1200 ppm (and up) and it seems the Mobil 1 Turbo Diesel Truck has that, however, the viscosity is 5W-40 which may be an issue. The cold viscosity may be too low to ensure sufficient protection to the tappets at startup and the 40 weight may be too high for tight tolerance bearings. Or perhaps, I have this all wrong? Thanks in advance.

Andrew

 

[UNC017]

Even with flat tappets, the actual cam-to-tappet pressure in a Northstar is a lot lower than in a high-performance pushrod v8. That is one advantage of overhead cams- the valve springs can be much lighter since there's less mass to return to the closed position. I wouldn't worry about running SM oil in a Northstar for the same reason I don't worry about it in my Jeep 4.0. The valve springs just don't create the kind of cam contact pressures that a muscle-era v8 engine has.

 

[Steve S]

Is the N. star an OHC engine?

 

[ekpolk]

Originally Posted By: Steve S
Is the N. star an OHC engine?


Yes, DOHC.

 

[Steve S]

So as far as flat tappet issue goes it is not a problem .

 

[1999nick]

Originally Posted By: abs
Okay, some interesting options listed, thanks ekpolk and damon! I still have some concerns though. I think the zinc levels need to be up around 1200 ppm (and up) and it seems the Mobil 1 Turbo Diesel Truck has that, however, the viscosity is 5W-40 which may be an issue. The cold viscosity may be too low to ensure sufficient protection to the tappets at startup and the 40 weight may be too high for tight tolerance bearings. Or perhaps, I have this all wrong? Thanks in advance.

Andrew


Just remember that all motor oil gets thinner as it gets hot. A 5W40 oil is thickest when its cold, so you have no worries about it being too thin when cold. Think of it as two oils: the 5W means that it is as thin as a straight 5W when cold, and the 40 means that it is as thick as a straight 40 when hot.

Tolerances have no effect, clearances might, but I can't imagine that Cadillac uses much different clearances than Mercedes Benz, which usually recommends a Xw40 motor oil.

 

[Steve S]

We have lots of reading with out the understanding of what is being read.

 

[crazyoildude]

Use 10w30 conventional... Reason is some of those engines are prone to leaking and the syn seems to leak more.. We see our fare share of those engines coming here due to oil leaks if its the front seal its easy but the rear is a lot of work and i tell most people to use 10w30 high mileage and that either slows the leak down or in some cases stops it..
I use the high mileage oil in some of my cars also one is a 95 seville with only 28000 miles because of a very slight leak we dont have time to fix..also if you get that start up tick once in a while the High Mileage oil will clean it and you wont hear that anymore..The start-up tick is nothing to worry about its common on those engines other than the occasional leaks and head gasket problems those engines are great (not to work on) but to drive they are reliable and have LOTS of power.. We had one here last month for a total rebuild it is owned and used as a car service-taxi and that one had over 300,000 taxi-limo miles..

 

[Steve S]

Ford engines last way longer in taxi services than that.

 

[ARCOgraphite]

Originally Posted By: ThirdeYe
I would recommend Shell Rotella T 10w30 for your Caddy...
+1 on the 10w30 RT, or Delvac 10w30 mixed fleet. The CJ4/SM diesel lightgrade oils are ok on a PCMO.

Parts/PLus (REAL) autopart stores usually have this 10w30

 

[wgtoys]

I would go for the Mobil 1 High Mileage 10w30. Available at your local WalMart for $22 for a 5 quart jug. Still SL rated due to high ZDDP levels.

 

[Leo]

Funny though, high ZDDP oils actually can cause more ring pack deposits. Personally in this situation I think Mobil 1 Turbo Diesel Truck is perfect for the situation.