I'm skeptical of the prevailing opinion I've seen here and elsewhere (especially Volvo forums) that oil viscosity (heavier = better or really argument at all) is critical for the proper functioning of the lifters. If I infer the logic correctly, the assumption is that thicker oil during both cold startup and running at normal temp is accounting for the fact that tolerances in the lifter body are larger due to wear over time and therefore the heavier oil will allow the lifters to keep their hydraulic pressure high enough to prevent disfunction (ticking). [Note that in the article below they say that heavy oil would be worse for lifter function, so I'm not entirely sure why heavy oil seems to help in Volvos.] I'm wondering if it's just a poor bandaid for a different problem. That problem being this: perhaps there is varnish/sludge/buildup on the lifter internals (check ball, plunger, spring - see the EHow link below for an explanation). Heavy oil will work as I mentioned previously (allow the corroded lifter internals to keep pressure longer because the slower flow rates mean that the lifter internals will empty more slowly thus keeping the internal hydraulic pressure high enough to function) but not fix the problem (varnish buildup preventing proper operation of the check ball, spring, or whatever). If this is correct, then the best course of action would be to use some sort of varnish solvent (AutoRx, Seafoam, high-detergent oil, or a combination of the above) to remove that buildup and allow the lifters (I'm guessing it would be primarily the check ball sealing action) to function properly. Thus lifter ticking has very little to do with oil weight, but oil weight can be used to partially mask the issue. If I'm right, perhaps we should be pointing people with lifter ticking to a high detergent oil or AutoRx or some other engine cleaning product that dissolves varnish?
"If this happens every time you start the engine, then it can mean that the oil in the engine is too heavy for the current temperatures, or that there is too much varnish in the lifter. Another indication that the hydraulic valve lifters aren't working is intermittent knocking, which can be caused by leakage at the check ball seat, which can be due to varnish or just particles getting in there that don't belong there. "
Read more: How Do Hydraulic Valve Lifters Work? | eHow.com http://www.ehow.com/how-does_5006538_hy ... z19XHcYbrD
http://www.ehow.com/how-does_5006538_hy ... -work.html
"If this happens every time you start the engine, then it can mean that the oil in the engine is too heavy for the current temperatures, or that there is too much varnish in the lifter. Another indication that the hydraulic valve lifters aren't working is intermittent knocking, which can be caused by leakage at the check ball seat, which can be due to varnish or just particles getting in there that don't belong there. "
Read more: How Do Hydraulic Valve Lifters Work? | eHow.com http://www.ehow.com/how-does_5006538_hy ... z19XHcYbrD
http://www.ehow.com/how-does_5006538_hy ... -work.html
