Less oil consumption due to PAO base?

[Hendo]

Hey All

I just checked the oil level in my '94 JZZ30 Soarer as I'm doing a long trip this weekend (1200 Kms) and to my delight found that my oil level hasn't changed in 2500Ks.

Using group III synths and HDDEOs my oil consumption was about 1L/5000ks (1 qt/ 3000 miles) and this has been constant for the last 5 years. I've just switched to a predominantly PAO oil (Anglomoil GEO 550 5w40) and I was wondering if anyone else has had a similar experience when switching to a grp IV oil.

I have heard the 1jz engine runs hot and I know the flash point of the new oil i'm using is 250 Degrees c (482F) so is the increased flash point causing this decreased consumption?

Some extra details-
1jz engine is turbocharged, 220K kms (136k miles)
valve stems have (did have?) slight leaks, small puff of smoke after restarting hot but none visible on decel.
last 2 OCIs (5000ks) were Delo400 15w40, Gulf western 10w40 ester syn/ mineral blend. Before this I had changed the rocker cover gaskets and cleaned around the cams (slight deposits)

 

[LargeCarManX2]

I would say....Yes! less consumption with an advanced base oil.

 

[The motor guy]

I do 100hr oil changes with amsoil in my lawn mower and I don't have to add anything for the first 50hrs. When I used regular oil i had to add some about every 5 or 6hrs.

 

[CATERHAM]

Oil consumption is related to two characteristics of an oil; the NOACK % and HTHSV.
The lower the NOACK volatility the better and a higher HTHSV (a thicker oil) means less oil consumption.
PAO based oils do generally have lower NOACK figures than GP III and dino oils.
Compare the spec's of both oils and the answer will become quite apparent.

 

[JHZR2]

In an engine that consumes oil, I've not seen any difference. In an engine that doesn't consume, I've not seen a practical difference.

 

[bluesubie]

Originally Posted By: JHZR2
In an engine that consumes oil, I've not seen any difference. In an engine that doesn't consume, I've not seen a practical difference.

Same here. And I've used used all kinds of base stock oils. Pennzoil Ultra, Red Line, various Mobil1's and Motuls.

-Dennis

 

[dave1251]

Originally Posted By: JHZR2
In an engine that consumes oil, I've not seen any difference. In an engine that doesn't consume, I've not seen a practical difference.


Well said.

 

[Hendo]

HTHS is 3.8, unsure of noack but its I'l keep my eye on it and report back

 

[Hendo]

Update: with 3800kms now the level is about 2mm down the dip stick, so the consumption is markedly less than it has been on the last 4 ocis. The color on the dipstick is also much lighter than usual (I realise that's not a indication of much) but this phenomenon with the decreased consumption could indicate higher flash point and lower noack as proposed previously by Caterham?

 

[mechtech2]

Originally Posted By: JHZR2
In an engine that consumes oil, I've not seen any difference. In an engine that doesn't consume, I've not seen a practical difference.


Me too.

[Viscosities the same, of course!]

For the OP, maybe a pcv system started working, or some cleaning made the rings seal better.

 

[Hendo]

Update:

The Alglomoil GEO550 was fantastic, and required no top up over the OCI, it ran to 7200kms and used approximately 300ml (a sizable improvement). I'ts the first oil I've been happy to break my 5000km (3k miles) usual OCI.

It's a pity its only sold in 20l drums and in my haste before Christmas I did a change with Valvoline Synpower 5w40. I've put 5300kms on this oil now in 1 month (lots of freeway!) and consumption and oil color is fine, about 300ml. (1/3 qt) It is still a dark gold on the dip stick but I can't accurately compare because 90% freeway Ks is not my normal pattern.

I'll get some more of the GEO550 and do a UOA on my next change

the stats of the Roadmaster GEO550 are:

5W/40 V@40=78.4 @100=13.6 VI= 178 Calcium= 3,257 Nitrogen=1,251 Phos= 903 Sulfur=2,562 Zinc=988 TBN=10.1 Sulfated Ash=1.26