Re: What Petrol for 1997 3.5 DOHC - LRP or Unleaded?
Posted: Mon Jan 24, 2011 2:30 pm
Unleaded petrol was introduced into South Africa in 1996 as the premium, higher octane grade across the country. There were two main issues to consider when switching to this grade, namely valve seat lubrication and octane quality. At coast, leaded 97 was replaced by unleaded 95, a 2 number drop which necessitated de-tuning in some cases to avoid knock. Also some older engines had soft valve seats which relied on the lead anti-knock package for lubrication. Without this, considerable wear took place showing as valve seat recession.
Any vehicle produced from 1996 onwards would be tolerant to unleaded fuel from a valve seat wear point of view, and should also have been able to tolerate the octane reduction.
I own a 1996 3.5 V6 and run it on either grade without any problem whatsoever as they are the same octane quality at the coast. LRP contains a valve seat lubrication package which would only be necessary on older vehicles having soft valve seats. You will also probably find that the detergent additive package in unleaded is more effective than in LRP, hence a cleaner engine.
Any vehicle produced from 1996 onwards would be tolerant to unleaded fuel from a valve seat wear point of view, and should also have been able to tolerate the octane reduction.
I own a 1996 3.5 V6 and run it on either grade without any problem whatsoever as they are the same octane quality at the coast. LRP contains a valve seat lubrication package which would only be necessary on older vehicles having soft valve seats. You will also probably find that the detergent additive package in unleaded is more effective than in LRP, hence a cleaner engine.