ACEA ratings

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Feb 21, 2008
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French Island
Hi folks, cool I am doing some readings on ACEA rating requirements. More specific in the section 2. Engine Tests, 2.7 Wear (6). It has limits on Cam wear outlet Cam wear inlet Cylinder wear Tappet wear Piston cleanliness Engine sludge avg. Etc. For this requirement, the limits are separated into two groups. ACEA ratings of A1/B1 and A3/B3 as one, A3/B4 and A5/B5 is another. A3/B4 and A5/B5 group has a lower limit allowance for wear. For example, Cam wear outlet (avg. max. wear 8 cams), 140 microm for A1/B1, A3/B3 and 120 microm for A3/B4, A5/B5. It seems that A3 spread across two categories of wear limits. As such, does the lower wear limits only applies to the diesel application of B4? In other words, do A3/B3 and A3/B4 actually have the same wear limits in petrol application? If the answer is no, wouldn’t it be more reasonable to name the rating A3/B4 to A4/B4..... wink
 
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Joined
Mar 13, 2013
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No. The A and B parts of the specification can not be separated, so the specifications are "A3/B3" and "A3/B4" - they are separate specs and, as you noted, the A3/B4 spec has a higher performance requirements, intended for severe service and/or extended drain. It is mostly a matter of history and legacy that means the specs are still named in this A/B way - the ACEA C specs also have gasoline and diesel performance but have a single letter to cover both.
 
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Nov 28, 2008
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Oklahoma
Originally Posted By: weasley
The A and B parts of the specification can not be separated, so the specifications are "A3/B3" and "A3/B4"
I don't understand this at all... The Valvoline Synthetic is A1 and A5 rated with no mention of a "B" rating. Is the B for diesel? If so, why does Mobil 0w-30 have the B rating?
 
Joined
Oct 30, 2002
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Originally Posted By: slidetaker
For example, Cam wear outlet (avg. max. wear 8 cams), 140 microm for A1/B1, A3/B3 and 120 microm for A3/B4, A5/B5.
FYI, Cam wear outlet for ACEA A1/B1 is <120 um as well.
 
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