Re: se or sf 30 wt oil ??

Posted by bill mart on January 02, 2013 at 05:40:01 from (69.204.65.189):

In Reply to: Re: se or sf 30 wt oil ?? posted by IaGary on January 02, 2013 at 05:35:06:

only problem that arises is the newer oils are lacking the phosphorus that many of the older engines need for lubrication. here is an article I found on the net.I find it interesting that each new rating letter makes the previous rating obsolete.Bill

The latest API service standard designation is SN for gasoline automobile and light-truck engines. The SN standard refers to a group of laboratory and engine tests, including the latest series for control of high-temperature deposits. Current API service categories include SN, SM, SL and SJ for gasoline engines. All previous service designations are obsolete, although motorcycle oils commonly still use the SF/SG standard.

All the current gasoline categories (including the obsolete SH), have placed limitations on the phosphorus content for certain SAE viscosity grades (the xW-20, xW-30) due to the chemical poisoning that phosphorus has on catalytic converters. Phosphorus is a key anti-wear component in motor oil and is usually found in motor oil in the form of zinc dithiophosphate. Each new API category has placed successively lower phosphorus and zinc limits, and thus has created a controversial issue of obsolescent oils needed for older engines, especially engines with sliding (flat/cleave) tappets. API, and ILSAC, which represents most of the worlds major automobile/engine manufactures, states API SM/ILSAC GF-4 is fully backwards compatible, and it is noted that one of the engine tests required for API SM, the Sequence IVA, is a sliding tappet design to test specifically for cam wear protection. Not everyone is in agreement with backwards compatibility, and in addition, there are special situations, such as "performance" engines or fully race built engines, where the engine protection requirements are above and beyond API/ILSAC requirements. Because of this, there are specialty oils out in the market place with higher than API allowed phosphorus levels. Most engines built before 1985 have the flat/cleave bearing style systems of construction, which is sensitive to reducing zinc and phosphorus. Example; in API SG rated oils, this was at the 1200-1300 ppm level for zinc and phosphorus, where the current SM is under 600 ppm. This reduction in anti-wear chemicals in oil has caused premature failures of camshafts and other high pressure bearings in many older automobiles and has been blamed for pre-mature failure of the oil pump drive/cam position sensor gear that is meshed with camshaft gear in some modern engines.

Replies:

• Re: se or sf 30 wt oil ?? ss55 06:55:24 01/02/13 (0)
• Re: se or sf 30 wt oil ?? Texasmark1 06:06:54 01/02/13 (3)
  • Re: se or sf 30 wt oil ?? GVSII 09:21:10 01/02/13 (0)
  • Re: se or sf 30 wt oil ?? buickanddeere 09:01:19 01/02/13 (0)
  • Re: se or sf 30 wt oil ?? bill mart 06:28:00 01/02/13 (0)

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