Atom 2/245 with 13,000 miles - part or fully sythetic?

[Sir Nick]

I've read loads on here regarding oils.

I have a simply question - should I use part or fully synthetic Castrol Magnetec?

Up to now I've been using the part synth...

Cheers

Nick

[AtomMadStew]

I think factory recommends semi. Cures any oil surging problems I think I remember Tom saying. (The grade eludes me - 0w 30 maybe the same as Honda ?!?)
I'm sure Professor Scherrer will be along shortly to confirm or correct. 

Stew

[John Scherrer]

http://www.atomclub.com/forum/index.php/topic,13174.msg242884.html#msg242884

See Tom's Reply #12

[Sir Nick]

Thanks John.  I see I even posted in that thread and forgot I did! 

It look s to me the part/fully synth is like the wings/no wings issue, a question of preference. 

Tom says that fully synth is a waste of money on a production engine, yet the fully synth is £8 cheaper than part synth currently!? 
http://www.amazon.co.uk/gp/product/B0042EUI16/ref=s9_simh_gw_p263_d0_i1?pf_rd_m=A3P5ROKL5A1OLE&pf_rd_s=center-3&pf_rd_r=13G6JPB00BC09G08FBXF&pf_rd_t=101&pf_rd_p=418449247&pf_rd_i=468294

Tom also goes on to say they had issues with 0w40 fully synth causing surge/pressure problems when hot - maybe the 5w/30 fully synth would not??

Round and round we go...

Cheers

Nick

[John Scherrer]

5W/30 is thinner (less viscous) than 0W/40 though at high temperature .. so it should be worse for oil surge in the sump?

[8407jeff]

Just an FYI--the K20 forums recommend a 5W-20 fully synthetic for the Honda K-series engines in base trim: 0W-30 or 5W-30 for more modified engines.  Word of mouth on the forums is that the thicker oils tend to cause a greater degree of cavitation.

According to Portland Nichols, the company that designed the gears in the Honda pump, the thinner synthetic helps the standard oil pump with its cavitation issues at high (8000+) RPM.  It isn't actually a pump problem.  The pickup just limits the amount of oil that can flow to the gears inside the pump and this causes the cavitation issues.  Of course you could just install the type S pump or even the S2K oil pump and forget about all the issues unless you are turning your engine more than 9K. 

Besides the cavitation issues with the standard oil pump, the cam towers also need extra oil at extremely high RPM, especially #5.

In the attached photo you can see a photo from L to R: standard oil pump, Type S, and S2K pump.  (note the size of the pickups....)

[John Scherrer]

Interesting post - thanks - I'd not thought about the fact that a thicker viscosity might be an issue with cavitation.

As far as I'm aware, there aren't many Atom engines that have been modified so that they can exceed the rev limited 8,600 but if the engine was coming apart for any (rare) reason and it was tracked a lot, it would make sense to upgrade the oil pump.

[Sir Nick]

So, setting aside the grade of oil for the moment, is part or fully synthetic best??

[John Scherrer]

Well re-reading Tom's statement in that earlier link ..

Fully Synthetic is a waste of money in a production engine designed to do 200K.
It has shown to be worse than part-synthetic in oil pressure/oil surge situations
It is advised in tuned engines such as the Mugen.

Main concern is lack of oil rather than quality.

So that suggests go with semi-synthetic ..

[AtomMadStew]

10w/40 semi magnatec it is then. Interesting comments about the type s or s2000 pump. Can it handle more than the regular oil pump? Any more info on that?

[8407jeff]

The standard oil pump is good for about 8300 RPM.  The type S is good for 8900RPM.  The S2K pumps are good to about 9500RPM.  The cam towers need modification above 9K anyway.