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Hey, I've seen various discussions on this, most ending that it's nothing more than snake oil and by the time any valve damage occurs, the engine is in need of a rebuild anyway for reaching such high mileage
For the price of it, I think, for peace if mind it can do no harm... or can it?
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bricol
Part of things
Posts: 290 
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I've been using a Texaco additive I bought in bulk a long time ago in my crossflow powered trials car - spends a lot of time idling on car trails, interspersed with lots of revs when on sections, and lots of sustained high revs on road sections on classic trials.
Without taking the head off, I can't tell if any damage is occurring, but in the tappets haven't needed adjusting to regain clearance in 20 yrs, so the valves can't be hammering too far into the head.
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ferny
Club Retro Rides Member
Posts: 986
Club RR Member Number: 13
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Lead additive questionferny
@ferny
Club Retro Rides Member 13
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Some brands are curse word. I used to use Castrol as it was regarded as one of the best, but then didn't bother.
If your engine was designed to be used in America (certainly California) there's a good chance it won't be needed. Their emission restrictions were much firmer before ours and engines were built to suit. There's also a theory of lead memory, where lead deposits embedded in the head negate the need for it. That would probably be a myth in my head. Another theory is that the metal has become hardened through heat cycles and constant tapping from use and is now already hard.
I've had valve seat recession on unleaded engines, converted engines and non-unlead engines. I used to drive them very hard and I also think luck plays a role.
Would I buy and use it now? Not on an old engine. But I'd keep an extra eye on the the adjustments and check more frequently than really needed.
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Last Edit: Apr 20, 2024 8:09:34 GMT by ferny
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What car, what year?
I had a 1967 Jaguar 420. 'Early' 1967 didn't have hardened exhaust valves and seat inserts, 'late' '67 did. But Jaguar didn't keep accurate enough records to be sure which engine numbers had which setup!
The 'Lead Memory' effect is real, but it 'wears off' especially when run at high loads/high speeds for extended periods.
The additives from reputable brands do work but are nowhere near as effective as lead and even more susceptible to high load/high speed.
If the car is a summer use back and forth to shows and the occasional Sunday Pub lunch run I use the additive - when I remember. When it needs its next top-end overhaul it will get exhaust valve seat inserts and new valves.
If you are talking about a Blower Bentley, Type 35 Bugatti or an Alldays and Onions......................
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micha1
Part of things
Posts: 30
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Jul 19, 2024 21:07:19 GMT
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consider all aluminium-heads to be unleaded friendly....in an aluhead it was necessary to fit steel valveseats from the factory.
by the way: i have driven plenty of ford x/flow powered cars.....hard driven ...even on racetracks....never used an addhitive...none of them had hardened valveseat inserts...and never had problems.
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ChasR
RR Helper
motivation
Posts: 10,307
Club RR Member Number: 170
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Lead additive questionChasR
@chasr
Club Retro Rides Member 170
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Jul 20, 2024 10:32:27 GMT
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consider all aluminium-heads to be unleaded friendly....in an aluhead it was necessary to fit steel valveseats from the factory. by the way: i have driven plenty of ford x/flow powered cars.....hard driven ...even on racetracks....never used an addhitive...none of them had hardened valveseat inserts...and never had problems. With ally heads, it depends on the quality of the valve seat. I've had ally headed cars suffer with Valve Seat Recession (VSR), but on LPG. I know with old Ford CVHs, some were safe and some were not. American derived stuff tends to be fine, as they had unleaded in play long before the UK did. We had 3 Mondeo 1.8 to 2.0s on LPG. The first Y reg was fine, even at 380k, where I was shocked that it had perfect compression, albeit worn stem seals and potentially oil control rings, which were iffy from the factory anyway in some cases/. Both the later 1.8 and 2.0, with a revised Duratec engine suffered from VSR. Some beetle heads suffer with VSR but that could also be down to cooling issues and cheap heads. However, on higher volume cars, they tend to fit softer valve seats to non-E85 cars. I believe warm up times are cited as one reason, and I'm sure cost will be. Ford changed the seats on the Focus FFV, since that was meant to be able to run on biofuel, and I know without doubt, one uk engine producer for a large car manufacturer in the UK uses different valve seats (and injectors) for E85 market engines IME, VSR can take anything from 10k to around 60k to happen. As long as it's factored into the costings, it's not that much if a deal breaker. |
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Last Edit: Jul 20, 2024 10:33:35 GMT by ChasR
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