Evening all
This will be a long one as I have been compiling for sometime now.
I have started/commented in several past oil related threads regarding the use of regular 15w40 as mower oil.
As stated before, I have always used a 15w40 engine oil in nearly everything I have. Occasionally, sae30 for some briggs that will really need it or 10w40 for some Honda.
I am no expert in chemistry or oil composition, however decided a few months ago to work out good oils for mower use.
I always purchase my oils from Autobarn – they regularly have oils out for between $10 and $15 for 5l.
My main options through their sales thus far have been:
Castrol Ultraclean 15w40 semi synthetic $2.4/l
Nulon Premium Mineral 15w40 $2/l
Gulf Western Premium Gold 15w40 $2/l
Valvoline Engine Armour 15w40 semisynthetic $2.5/l
For interest, I have included Penrite Vantage semisynth 15w40. This can occasionally be had for around $20.
Penrite mower sae 30 and Gulf western mower SAE30 are also included in this comparo
The main things I consider to be of important for our application are resistance to shear, ZDDP zinc, viscosity at 40c and 100c and sulphated ash level.
Zinc protects flat tappet engines from wear and
sulphated ash helps neutralise the acids which build in the oil from the relatively loose build tolerances (cough Briggs haha)
Armed with a few months of reading, I recently sent the oil companies some emails regarding the ZDDP levels. Here are my results (compiled with infor from MSDS and PI sheets)
Castrol Ultraclean
Visc @100 14.5
Visc @40 111
ZDDP ppm 870
Sulphated ash % 0.9
Nulon
Visc @100 15
Visc @40 121
ZDDP ppm 1300
Sulphated ash % 0.8
GW
Visc @100 15
Visc @40 107
ZDDP ppm 870
Sulphated ash % 1.2
Valvoline
Visc @100 15
Visc @40 116
ZDDP ppm 1000
Sulphated ash % (not shown, but my calc approx 0.85)
Penrite
Visc @100 15
Visc @40 104
ZDDP ppm 1050
Sulphated ash % 1.2
GW sae30
Visc @100 11
Visc @40 95
ZDDP ppm 1000
Sulphated ash % 1.1
Penrite SAE30
Visc @100 11
Visc @40 90
ZDDP ppm 1117
Sulphated ash % 0.67
Please note – if you purchased the GW 15w40 before july, there is a good chance you have the version complying with API SL (more zinc). The label states ‘Zinc enhanced’.
This should be around the 1200 mark.
My opinion on valvoline is yet to become clear - I haven't used it long enough to see the shear stability. 4 bottles were bought in July, so I will know soon enough
Likewise, GW used to be API SL and very good, but I am not in a position to comment on the new SN.
I will personally stick with Nulon - my 40L stash of ultraclean won't go into anymore mowers. Although I wouldn't hesitate to get the new SN GW for flushing oil.
Having used the Castrol for a while now, it definitely gets the sludge out fast, but seems to have lower shear resistance long term. After 15+ mows, the quantums tend to burn oil on start up.
I have no problems with it in water cooled engines and my Hyundai runs perfectly on it, but air cooled put significant stress on oils. My remaining 40l will be going into the Tuscon (4ish L per change) and Aurion (6l ish)
Overall, flushing oil makes no difference – it isn’t in there for long enough to do anything anyway.
Plus, anything is better than the sludge normally found in briggs sumps.
So, in summary, for Briggs:
All this is probably useless information
